Center for Pulsed Power and Power Electronics.
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Dr. Magne Kristiansen

Professor Emeritus
Paul Whitfield Horn Professor of Electrical and Computer Engineering

Contact Information

Department of Electrical and Computer Engineering
Texas Tech University
Lubbock, TX 79409-3102

Phone: (806)742-2224
Fax: (806)742-1281
M.kristiansen@ttu.edu

Education

Research Interests

Experience

Projects

Awards and Professional Societies

Publications


Journal

Publication Year:  2014
+ Conditioning of carbon fiber cathodes in UHV-sealed tubes at 200 A/cm²
  J. Parson, C. Lynn, J. Mankowski, M. Kristiansen, A. Neuber, J. Dickens, "Conditioning of carbon fiber cathodes in UHV-sealed tubes at 200 A/cm²," IEEE Trans. On Plasma Sci. 42, 2007-2014 (2014).
Abstract:  This paper presents a study on outgassing and electrical conditioning for three carbon fiber cathode types in a vacuum-sealed, high-power microwave virtual-cathode-oscillator (vircator) that operates in the low 1e-9 torr pressure regime. The three cathode types consist of a bare bimodal fiber structure, a bare unimodal fiber structure, and a cesium-iodide coated bimodal fiber structure with identical fiber coverage of 2% by area with a surface area of ~20 cm2. The electrodes are cleaned by a 1.2 kW, argon/oxygen microwave plasma prior to complete vircator assembly, followed by a 300 °C bake-out for 72 h. Each cathode was pulsed in a single pulse operation by an 80 J, low inductance Marx generator with an approximate pulsewidth of 100 ns full-width at half-maximum for 10000 current pulses. The data presented includes individual gas constituents, high-speed intensified charge coupled device (ICCD) imaging, and voltage and current waveforms. The conditioning process resulted in a gas load reduction of ~80% overall, with the indication that the bare bimodal fiber structure performed the best as diode power increased throughout the experiment, while the power decreased for the other tested cathode types.

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Publication Year:  2012
+ An Explosively Driven High Power Microwave Pulsed Power System
  M. Elsayed, A. Neuber, J. Dickens, J. Walter, M. Kristiansen, and L. Altgilbers, "An Explosively Driven High Power Microwave Pulsed Power System," Rev. Sci. Instrum. 83, 024705 (2012).
Abstract:  The increased popularity of high power microwave systems and the various sources to drive them is the motivation behind the work to be presented. A stand-alone, self-contained explosively driven high power microwave pulsed power system has been designed, built, and tested at Texas Tech University's Center for Pulsed Power and Power Electronics. The system integrates four different sub-units that are composed of a battery driven prime power source utilizing capacitive energy storage, a dual stage helical flux compression generator as the main energy amplification device, an integrated power conditioning system with inductive energy storage including a fast opening electro-explosive switch, and a triode reflex geometry virtual cathode oscillator as the microwave radiating source. This system has displayed a measured electrical source power level of over 5 GW and peak radiated microwaves of about 200 MW. It is contained within a 15 cm diameter housing and measures 2 m in length, giving a housing volume of slightly less than 39 l. The system and its sub-components have been extensively studied, both as integrated and individual units, to further expand on components behavior and operation physics. This report will serve as a detailed design overview of each of the four subcomponents and provide detailed analysis of the overall system performance and benchmarks.

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+ Experimental and Theoretical Evaluation of Surface Coated Exploding Wires
  J. Stephens, A. Neuber, and M. Kristiansen, "Experimental and Theoretical Evaluation of Surface Coated Exploding Wires," Phys. Plasmas 19, 032702 (2012).
Abstract:  This paper discusses the effect of surface coatings on exploding wire behavior. Three different surface coatings of different thicknesses and materials have been studied, each with a 99.99% pure silver conducting core. Experimentally, the wires are subjected to peak current densities in excess of 107 A/cm2 on a microsecond time scale. High Speed intensified Charge-Coupled Device (iCCD) images. A theoretical one-dimensional finite difference model has been developed to predict wire behavior and determine the mechanism(s) responsible for the deviations in behavior induced by the presence of a surface coating.

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Publication Year:  2010
+ Capacitor Evaluation for Compact Pulsed Power
  E. J. Matthews, M. Kristiansen, A. A. Neuber, "Capacitor Evaluation for Compact Pulsed Power", IEEE Transaction on Plasma Science 38, 500-508 (2010)
Abstract:  An evaluation of the energy density and efficiency of high-voltage capacitors, from various manufacturers, at voltages above their rated level is presented. Characteristics such as decreasing capacitance, decreasing efficiency, and increasing energy density are described. Data are taken from eight capacitors; six of which are composed of varying nonlinear ceramic materials as a dielectric, and the remaining two are wound capacitors, which were chosen to exhibit their linear characteristics. Rapid (1-100 ms) charging and discharging, similar to that of a generator operation at a repetition rate of more than 10 Hz with an ~100-ns pulse, were the conditions simulated in this particular test setup.

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+ Characterization of a 50 J Linear Transformer Driver
  David Matia, Hermann Krompholz, Travis Vollmer, Andreas Neuber, Michael Giesselmann, Magne Kristiansen, "Characterization of a 50 J Linear Transformer Driver", Proceedings of the 2010 IEEE International Power Modulator and High Voltage Conference, May 23-27, 2010, Atlanta, GA.
Abstract:  A detailed characterization of a 50 J linear transformer driver (LTD) stage is presented. The specific goal of the design is to achieve energy densities superior to typical Marx generators, such as a 500 J compact Marx generator previously designed and built at Texas Tech's Pulsed Power lab. Experimental and analytical techniques for determining circuit elements and especially parasitic elements were used, yielding the magnetizing, primary and secondary leakage inductances associated with the transformer, core saturation effects, parasitic capacitances, the inductance of the pulse discharge circuit, and losses in both copper and the deltamax core. The investigations into these characteristics were carried out using both sinusoidal excitation from 1 kHz to 20 Mhz, and pulsed excitation with rise times down to 5 ns. Pulse amplitudes were varied to cover both the linear and saturation regimes of the core. Distributed parasitic capacitances and the inductance of the pulse discharge circuit were estimated analytically and compared with experimental results. This work was carried out to seek an ideal arrangement of the capacitors and switches on the LTD stage and gain a better basic understanding of fast rise time pulse transformers. Adjustments to the 50 J stage are proposed based on this characterization in order to optimize a future ten stage, 500 J assembly.

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+ Modeling and Simulation of Simple Flux-Trapping FCGs Utilizing PSpice Software
  Young, A.; Neuber, A.; Kristiansen, M.; "Modeling and Simulation of Simple Flux-Trapping FCGs Utilizing PSpice Software"; Plasma Science, IEEE Transactions on Volume: 38 , Issue: 8 , Part: 1; Publication Year: 2010 , Page(s): 1794 - 1802
Abstract:  A novel modeling and simulation method for flux-trapping flux-compression generators (FT-FCGs) is presented, which utilizes PSpice circuit-simulation software to solve complex differential equations derived from circuit analysis. The primary motivation for the model development is the desire for a technique to rapidly design and prototype FT-FCGs for use as drivers in high-power microwave sources. The derivation of FT-FCG equations will be given, both in the ideal (lossless) and nonideal cases. For the nonideal case, three flux conservation coefficients are added to the equations to account for intrinsic flux loss in the circuit. Time-varying inductance curves are calculated using zero-dimensional models found in literature and adapted to fit this model. A simple FT-FCG design is used as an example to show the steps taken to complete a simulation. The same design was also fabricated and tested for comparison with predicted results from the model. A comparison of the waveforms acquired through simulation and experiment was found to result in good agreement for a given set of values for the flux conservation coefficients. A discussion of the derived equations, both lossless and nonideal, is given, as well as a discussion on the investigation of the impact of the three flux constants on the circuit. Analysis is offered on the results of this investigation, and conclusions are given on the effectiveness of this model to predict FT-FCG behavior.

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+ Simulation of Compact Explosively-Driven Ferroelectric Generators
  D. Bolyard, T. Krile, A. Neuber, M. Kristiansen, "Simulation of Compact Explosively-Driven Ferroelectric Generators", IEEE Trans. On Plasma Sci. 38, 1008 - 1014 (2010)
Abstract:  Pressure simulations have been performed for several experimental explosively driven ferroelectric generators, with 2.54-cm-diameter PZT EC-64 discs as the ferroelectric material, using the hydrodynamic code system CTH, developed by Sandia National Laboratories. An empirical relationship was found between the results of the pressure simulations and the output voltages of the experimental generators, and an algorithm was generated to convert the simulated pressure into open-circuit voltage. This empirical algorithm has been applied to simulations of different experimental ferroelectric generators, and the results show a good correlation when compared to the corresponding experimental open-circuit output voltages. The experimentally achieved output voltages normalized for a thickness range from 14 to 34 kV/cm

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Publication Year:  2009
+ Optimization of an FCG Based High Power Microwave System using Nonexplosive Pulsed Power
  C. Davis, A. Neuber, A. Young, J. Walter, J. Dickens, M. Kristiansen, "Optimization of an FCG Based High Power Microwave System using Nonexplosive Pulsed Power," IEEE Trans. On Plasma Science, 27, 2321- 2327 (Sept. 2009)
Abstract:  This paper presents a nonexplosive pulsed-power system that replicates the output current waveform of a flux compression generator (FCG). The primary purpose of this system is to efficiently test the power conditioning components of an explosively driven HPM system, while drastically reducing the time between tests which are inherent with explosive experiments. The power conditioning system (PCS) of the HPM system includes an energy-storage inductor, an electroexplosive opening switch (fuse), and a peaking gap and serves to match the FCG output characteristics with the HPM diode load requirements. A secondary purpose of the nonexplosive test bed is to provide data points which could be directly compared with those from explosively driven experiments. For this reason, a reflex-triode virtual cathode oscillator (vircator) was connected to the output of the nonexplosive system, and the results of which were compared with similar testing done with an FCG and a compact Marx generator. Since the behavior of the fuse is known to play a critical role in the performance of the PCS, a study was performed on the effect of different fuse designs on the overall performance of the PCS. Specifically, the quality of the electrical connection between the fuse wire array and the rest of the system was tested. Fuse design experiments were conducted with the nonexplosive test bed firing into a water resistor dummy load, which showed a 13% increase in peak load voltage and more than an 11% increase in energy transfer for fuses with improved wire-electrode connection strength. Some basic rules about fuse design, as well as conclusions on the performance of the PCS when driving an HPM load, are given.

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+ Recent Advances in Explosive Pulsed Power
  L.L. Altgilbers, A.H. Stults, M. Kristiansen, A. Neuber, J. Dickens, A. Young, T. Holt, M. Elsayed, R. Curry, K. O’Connor, J. Baird, S. Shkuratov, B. Freeman, D. Hemmert, F. Rose, Z. Shotts, Z. Roberts, W. Hackenberger, E. Alberta, M. Rader, A. Dougherty, "Recent Advances in Explosive Pulsed Power,", Journal of Directed Energy, 3, 1-43 (2009)
Abstract:  Not Available
Publication Year:  2008
+ Compact Electro-Explosive Fuses for Explosive Driven Pulsed Power
  D. R. McCauley, D. W. Belt, J. J. Mankowski, J. C. Dickens, A. A. Neuber, and M. Kristiansen, "Compact Electro-Explosive Fuses for Explosive Driven Pulsed Power", to appear in IEEE Transactions on Plasma Science (2008)
Abstract:  Compact electroexplosive fuses (EEFs) as part of an explosively driven system are of interest for the one-time single-shot generation of high-power pulses. For instance, the transition from a very large driving current produced by an explosively driven flux compression generator (FCG), i.e., low impedance, to a large voltage spike delivered to the load, i.e., high impedance, can be done using an inductive storage system and an EEF. Typically, the EEF can be as large as, if not larger than, the current driver attached to it, thus making it one of the largest components in the system. Reduction in the size of the fuse will allow for size reductions of the entire high-power microwave (HPM) system. The goal of optimizing an EEF as an opening switch is to produce the greatest voltage multiplication possible to drive a load under physical size constraints. To optimize the fuse, several parameters are taken into account, including, but not limited to, fuse material, fuse length, fuse shape, and quenching medium. Individual optimization of these parameters will lead to complete optimization of an EEF, therefore resulting in a compact fuse capable of consistently producing maximum voltage multiplication for HPM systems.

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+ Fast-charging compact seed source for magnetic flux compression generators
  M. Elsayed, M. Kristiansen, A. Neuber, Fast-charging compact seed source for magnetic flux compression generators, 2008 Review of Scientific Instruments. Vol. 79, 124702.
Abstract:  Flux compression generators (FCGs) are some of the most attractive sources of single-use compact pulsed power available today due to their high energy density output and mobility. Driving FCGs requires some seed energy, which is typically provided by applying a high seed current, usually in the kiloampere range for midsized helical FCGs. This initial current is supplied by a high-current seed source that is capable of driving an inductive load. High-current seed sources have typically been comprised of discharging large capacitors using spark gaps and overvoltage triggering mechanisms to provide the prime power for FCGs. This paper will discuss a recent design of a self-contained (battery powered with full charge time less than 40 s), single-use compact seed source (CSS) using solid-state components for the switching scheme. The CSS developed is a system (0.005 m3 volume and weighing 3.9 kg) capable of delivering over 360 J (∼12 kA) into a 5.20 μH load with a trigger energy of microjoules at the TTL triggering level. The newly designed solid-state switching scheme of the CSS incorporates off-the-shelf high-voltage semiconductor components that minimize system cost and size as necessary for a single-use application. A detailed evaluation of the CSS is presented primarily focusing on the switching mechanics and experimental characterization of the solid-state components used in the system.

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+ High Power Microwave System
  T. Holt, A. Young, M. Elsayed, J. Walter, A. Neuber, and M. Kristiansen, "High Power Microwave System", to appear in IEEE Transactions on Plasma Science (2008)
Abstract:  Not Available
+ Images From the Development of a High-Power Microwave System
  T. Holt, A. Young, M. Elsayed, J. Walter, A. Neuber, and M. Kristiansen, Images From the Development of a High-Power Microwave System, IEEE Transactions on Plasma Science 36, 1414-1415 (2008).
Abstract:  A recently developed self-contained compact single-shot high-power microwave (HPM) system was tested and characterized. The explosive-driven system utilizes a reflex triode virtual cathode oscillator (vircator) as the HPM source. An open-shutter image acquired with a digital single-lens reflex camera during operation was used to show plasma development extending beyond the anode-cathode gap of the vircator. The plasma's self-emission is due to ionized material eroded and desorbed from both the cathode and the anode.

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+ Low-Jitter Triggered Spark Gap With High-Pressure Gas Mixtures
  Yeong-Jer Chen; Mankowski, J.J.; Dickens, J.C.; Walter, J.; Kristiansen, M.; Low-Jitter Triggered Spark Gap With High-Pressure Gas Mixtures; Plasma Science, IEEE Transactions on Volume 36, Issue 5, Part 3, Oct. 2008 Page(s):2546 - 2553 ; Digital Object Identifier 10.1109/TPS.2008.2004366
Abstract:  Recent attention to impulse antenna phased array has necessitated the need to develop a reliable high-voltage high-repetition-rate switch that will operate with ultralow jitter. An ideal jitter of a small fraction of the rise time is required to accurately synchronize the array to steer and preserve the rise time of the radiated pulse. This paper presents the impact that gases and gas mixtures have on switch performance which includes recovery rate and, in particular, jitter. A 50-Omega 1-nF pulse-forming line is charged to 30 kV and provides the low inductance voltage source to test the different gases. Triggering is provided by a solid-state opening switch voltage source that supplies >100-kV 10-ns rise-time pulses at a rep rate of up to 1 kHz in burst mode. A hermetically sealed spark gap with a Kel-F lining is used to house the switch and high-pressure gas. The system includes a gas-mixing chamber that can mix various gases up to 2000 psi. Gases tested include dry air, H2, N2, and SF6. Switch operations in 30 kV and 10 Hz have shown reliable subnanosecond jitter times with pure gases, including dry air, H2, N2, and with H2 - N2 and N2 - SF6 gas mixtures. The system was then modified for 50-kV 100-Hz operations with data collected for each of the pure gases. Recovery was monitored with no major problems at the 100-Hz operation, and subnanosecond jitter results for H2 , N2, and SF6 are also recorded.

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+ Secondary Arc Formation Within a Distributed Energy Railgun
  Karhi, R.W.; Mankowski, J.J.; Dickens, J.C.; Kristiansen, M.; Wetz, D.A.; Secondary Arc Formation Within a Distributed Energy Railgun; Plasma Science, IEEE Transactions on Volume 36, Issue 5, Part 3, Oct. 2008 Page(s):2738 - 2746 Digital Object Identifier 10.1109/TPS.2008.2004228
Abstract:  Experimental results comparing a breech-fed scheme and two distributed energy schemes for a free-running arc are presented. Analysis and observations of the issues associated with distributed energy switching of a plasma arc in the railgun are explored. The use of a free-running arc allows experiments to emulate the ablation and restrike phenomenon of a plasma armature railgun at high speeds (> 5 km/s) without the requirement of a large amount of stored energy. Numerous experimental tests were conducted to investigate the dynamics of plasma arcs within a distributed energy source railgun. Variations of switch timing, bore pressure, bore material, current amplitude, and current pulse length within each stage have been tested. These data reveal important design parameters for distributed energy railguns. The arc length, stage length, and stage trigger timing play a crucial role in distributed energy railgun performance. Failure to take these parameters into consideration will result in velocity reduction through plasma arc restrike and/or splitting.

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+ Utilization of a Nonexplosive Test Bed for Flux-Compression-Generator Electroexplosive Opening Switches
  D. W. Belt, J. J. Mankowski, A. A. Neuber, J.C. Dickens, M. Kristiansen, Utilization of a Nonexplosive Test Bed for Flux-Compression-Generator Electroexplosive Opening Switches, IEEE Transactions on Plasma Science 36, 2684 - 2690, (2008).
Abstract:  Helical flux compression generators (HFCGs) of a 50-mm form factor have been shown to produce output energies on the order of ten times the seeded value and a typical deposited energy of 3 kJ into a 3-muH inductor. One way to drive a high-power microwave source with an HFCG is by power conditioning, such as an inductive energy storage system (IESS). The output performance of the IESS is contingent upon the opening switch scheme, usually an electroexplosive fuse. Our previous work involving fuse parameter characterization has established a baseline for potential fuse performance. In order to optimize the electroexplosive wire fuse, we have constructed a nonexplosive test bed which simulates the HFCG output with high accuracy. We have designed and implemented a capacitor-based magnetic switching scheme to generate the near-exponential rise of the HFCG. The use of the nonexplosive HFCG test bed will allow the verification of scalability of the fuse parameter model and also allow testing of exotic fuse materials. The nonexplosive test bed has provided a more efficient method for electroexplosive switch development and has allowed us to expand the study of opening switches. We will also discuss the a priori calculated baseline fuse design and compare the experimental results of the gold-wire-material with the silver-wire-material baseline design. With the results presented, an accurate PSpice model applicable to our 45-kA HFCG systems will be available.

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Publication Year:  2007
+ A Bench Top Railgun With Distributed Energy Sources
  Mankowski, J.; Dickens, J.; Giesselmann, M.; McDaniel, B.; McHale, B.; Kristiansen, M.; IEEE Transactions on Magnetics, Volume 43, Issue 1, Part 2, Jan. 2007 Page(s):167 - 169
Abstract:  Experimental results of a distributed energy source railgun are presented. Distributed energy source railguns were first proposed by Marshal in an asynchronous scheme and later by Parker synchronously. Both schemes employ a "traveling excitation wave" to push the projectile along the rail. The primary advantages of such a scheme over the common breech-fed is higher efficiency due to less energy remaining in the rail and lower rail resistive loses. Another advantage is the reduction in the probability of re-strike. However, these advantages are achieved at a cost of higher switching complexity. As a proof of principle experiment, we have constructed a bench-top solid armature railgun with distributed energy sources. Instead of a single, capacitive, breech-fed, energy source, the current is supplied by two storage capacitor banks, placed at different positions along the rail. The switching configuration, which requires a dedicated switch at each capacitor, is realized with sold state switches. The railgun is diagnosed in order to evaluate performance and to appropriately trigger the switches. In addition, experimental results are compared to simulation

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+ Cathode and Anode Optimization in a Virtual Cathode Oscillator
  Chen, Y.; Mankowski, J.; Walter, J.; Kristiansen, M.; Gale, R.; IEEE Transactions on Dielectrics and Electrical Insulation, [see also IEEE Transactions on Electrical Insulation] Volume 14, Issue 4, Aug. 2007 Page(s):1037 - 1044
Abstract:  Not Available

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+ Interface Breakdown During High-Power Microwave Transmission
  Neuber, A. A.; Edmiston, G. F.; Krile, J. T.; Krompholz, H.; Dickens, J. C.; Kristiansen, M.; IEEE Transactions on Magnetics, Volume 43, Issue 1, Part 2, Jan. 2007 Page(s):496
Abstract:  The major limiting factor in the transmission of narrowband high-power microwaves (HPM) has been the interface between vacuum-vacuum or even more severely between vacuum-air if HPM are to be radiated into the atmosphere. Extensive studies have identified the physical mechanisms associated with vacuum/dielectric flashover, as opposed to the mechanisms associated with dielectric/air flashover, which are not as well known. Due to the high electron collision frequencies (in the terahertz range) with the background gas molecules, established mitigation methods and concepts of vacuum/dielectric flashover will have to be re-evaluated. The primarily limiting factors of HPM transmission through a dielectric/air interface are presented based on recent experiments at 2.85 GHz. The physics of the involved mechanisms and their practical ramifications are discussed. The potential of surface roughness/geometry for flashover mitigation is addressed as

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Publication Year:  2006
+ Design and implementation of a flux compression generator nonexplosive test bed for electroexplosive fuses
  D. Belt, J. Mankowski, A. Neuber, J. Dickens, and M. Kristiansen Center for Pulsed Power and Power Electronics, Texas Tech University, Lubbock, Texas 79409-3102; Departments of Electrical, Texas Tech University, Lubbock, Texas 79409-3102; and Computer Engineering and Physics, Texas Tech University, Lubbock, Texas 79409-3102 Review of Scientific Instruments, Vol 77, Article 094702 (2006) (7 pages)
Abstract:  Helical flux compression generators (HFCGs) of a 50 mm form factor have been shown to produce output energies on the order of ten times the seeded value and a typical deposited energy of 3 kJ into a 3 µH inductor. By utilizing an electroexplosive fuse, a large dI/dt into a coupled load is possible. Our previous work with a nonoptimized fuse has produced ~100 kV into a 15 load, which leads into a regime relevant for high power microwave systems. It is expected that ~300 kV can be achieved with the present two-stage HFCG driving an inductive storage system with electroexploding fuse. In order to optimize the electroexplosive wire fuse, we have constructed a nonexplosive test bed which simulates the HFCG output with high accuracy. We have designed and implemented a capacitor based, magnetic switching scheme to generate the near exponential rise of the HFCG. The varying inductance approach utilizes four stages of inductance change and is based upon a piecewise linear regression model of the HFCG wave form. The nonexplosive test bed will provide a more efficient method of component testing and has demonstrated positive initial fuse results. By utilizing the nonexplosive test bed, we hope to reduce the physical size of the inductive energy storage system and fuse substantially. ©2006 American Institute of Physics

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+ Design and implementation of a flux compression generator nonexplosive test bed for electroexplosive fuses
  D Belt, J Mankowski, A Neuber, J Dickens, M Kristiansen, "Design and implementation of a flux compression generator nonexplosive test bed for electroexplosive fuses" Review of scientific instruments 77, 094702
Abstract:  Not Available
+ Similarities Of Dielectric Surface Flashover at Atmospheric Conditions for Pulsed Unipolar and RF Excitation
  J. Krile, G. Edmiston, K. Morales, A. Neuber, H. Krompholz, and M. Kristiansen, Similarities Of Dielectric Surface Flashover at Atmospheric Conditions for Pulsed Unipolar and RF Excitation, Laser Physics in Special Issue "Plasma, Beams, and Lasers" Dedicated to Professor Gennady A. Mesyats on his 70th Birth Anniversary, vol. 16, pp. 194-201, 2006.
Abstract:  Not Available
+ Similarities of dielectric surface flashover under atmospheric conditions for pulsed unipolar and RF excitation
  J Krile, G Edmiston, K Morales, A Neuber, H Krompholz, M Kristiansen, "Similarities of dielectric surface flashover under atmospheric conditions for pulsed unipolar and RF excitation" Laser Physics 16 (1), 194-201
Abstract:  Not Available
+ The Impact of Field Enhancements and Charge Injection on the Pulsed Breakdown Strength of Water
  Wetz, D.A.; Mankowski, J.J.; Dickens, J.C.; Kristiansen, M.; IEEE Transactions on Plasma Science, Volume 34, Issue 5, Part 1, Oct. 2006 Page(s):1670 - 1679
Abstract:  A unique theoretical model of the breakdown mechanism in water has been developed and further tested in both simulation software and experimentation. The conducted experiments test the degree to which electrode material, surface roughness, and surface area impact the dielectric strength of water. Voltage pulses with respective rise times of roughly 200 and 20 ns were applied to a water test gap producing electric fields in excess of 1.5 MV/cm. In experiments testing various electrode materials, thin film coatings of various metallic alloys and oxides were applied to Bruce-profiled stainless steel electrodes, with an effective area of 5$hboxcm^2$, through ion beam deposition. Similar Bruceprofiled stainless steel electrodes with surface roughness ranging from 0.26 to 1.96$muhboxm$and effective areas ranging from 0.5 to 75$hboxcm^2$were used in the study of surface roughness and area. Additionally, shadowgraph images of a point plane geometry were taken to further understand the breakdown processes that occur.

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Publication Year:  2005
+ Design and optimization of a compact, repetitive, high-power microwave system
  YJ Chen, AA Neuber, J Mankowski, JC Dickens, M Kristiansen, R Gale, "Design and optimization of a compact, repetitive, high-power microwave system" Review of scientific instruments 76, 104703
Abstract:  Not Available
+ Design and optimization of a compact, repetitive, high-power microwave system
  Y. J. Chen, A. A. Neuber, J. Mankowski, J. C. Dickens, and M. Kristiansen Texas Tech University, Center for Pulsed Power and Power Electronics, Lubbock, Texas 79409-3102 R. Gale Texas Tech University, Nano Tech Center, Lubbock, Texas 79409-3102 Review of Scientific Instruments, Vol 76, Article 104703 (2005) (8 pages)
Abstract:  The electrical characteristics and design features of a low inductance, compact, 500 kV, 500 J, 10 Hz repetition rate Marx generator for driving an high-power microwave (HPM) source are discussed. Benefiting from the large energy density of mica capacitors, four mica capacitors were utilized in parallel per stage, keeping the parasitic inductance per stage low. Including the spark-gap switches, a stage inductance of 55 nH was measured, which translates with 100 nF capacitance per stage to ~18.5 characteristic Marx impedance. Using solely inductors, ~1 mH each, as charging elements instead of resistors enabled charging the Marx within less than 100 ms with little charging losses. The pulse width of the Marx into a matched resistive load is about 200 ns with 50 ns rise time. Repetitive HPM generation with the Marx directly driving a small virtual cathode oscilator (Vircator) has been verified. The Marx is fitted into a tube with 30 cm diameter and a total length of 0.7 m. We discuss the Marx operation at up to 21 kV charging voltage per stage, with repetition rates of up to 10 Hz in burst mode, primarily into resistive loads. A lumped circuit description of the Marx is also given, closely matching the experimental results. Design and testing of a low cost, all-metal Vircator cathode will also be discussed. ©2005 American Institute of Physics

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+ The Impact of Surface Conditioning and Area on the Pulsed Breakdown Strength of Water
  Wetz, D.A., Jr.; Truman, K.P.; Mankowski, J.J.; Kristiansen, M.; IEEE Transactions on Plasma Science, Volume 33, Issue 4, Part 1, Aug. 2005 Page(s):1161 - 1169
Abstract:  Experimental results are presented on the degree to which electrode surface conditioning and surface area impact the dielectric strength of water. The applied pulse to the test gap reached electric field levels greater than 1.5 MV/cm with risetimes around 200 and 50 ns, respectively. The test gap is composed of 304 stainless steel electrodes machined with a Bruce profile. Electrode surface roughness ranged from 0.34 to 1.41$muhbox m$and effective areas ranged from 0.5 to 75$hbox cm^2$. Additional results are presented on the pulsed breakdown strength of Rexolite with various surface finishes ranging from .025 to 5.715$muhbox m$. Conclusions are made as to the effect electrode surface area and surface roughness has on the holdoff voltage of water dielectric systems. Conclusions are also made as to the impact of the surface condition of Rexolite has on its bulk breakdown strength.

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Publication Year:  2004
+ Approximate Analytical Solitopms for the Space-Charge-Limited Current in One-Dimensional and Two-Dimensional Cylindrical Diodes
  "Approximate Analytical Solitopms for the Space-Charge-Limited Current in One-Dimensional and Two-Dimensional Cylindrical Diodes", Physics of Plasmas, 11, 6 3278-3283, June 2004 (with James Dickesn, L.L. Hatfield, and Eun-Ho Choi).
Abstract:  Not Available
+ Approximate Analytical Solutions for the Space-Charge-Limited Current in One-Dimensional and Two-Dimensional Cylindrical Diodes
  "Approximate Analytical Solutions for the Space-Charge-Limited Current in One-Dimensional and Two-Dimensional Cylindrical Diodes", Physics of Plasmas, June 2004 11 6, 3278-3283, (with James Dickens, L.L. Hatfield, and Eun-Ho Choi).
Abstract:  Not Available
+ Microwave frequency determination mechanisms in a coaxial vircator
  Xupeng Chen; Dickens, J.; Mankowski, J.; Hatfield, L.L.; Eun Ha Choi; Kristiansen, M.; IEEE Transactions on Plasma Science, Volume 32, Issue 5, Part 1, Oct. 2004 Page(s):1799 - 1804
Abstract:  Traditionally, the radiated microwave frequency in a coaxial vircator is considered to be determined primarily by the virtual cathode oscillation frequency and the electron reflection frequency. In this paper, some experiments showing different results are reported. In particular, the E-beam is observed to play an important role in the cavity formation. Some possible explanations, including a virtual cavity concept, are proposed. The cavity resonance effect on a coaxial virtual cathode oscillator with different geometries has been investigated in detail. Investigation of the E-beam performance will improve understanding of the interaction between the E-beam and microwaves, which is a key for determining the microwave frequency. These results are helpful in optimizing the design of a cylindrical diode to avoid microwave frequency shifting and mode competition.

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+ Quantification of ohmic and intrinsic flux losses in helical flux compression Generators
  Hernandez, J.C.; Neuber, A.A.; Dickens, J.C.; Kristiansen, M.; IEEE Transactions on Plasma Science, Volume 32, Issue 5, Part 1, Oct. 2004 Page(s):1902 - 1908
Abstract:  Helical magnetic flux compression generators (MFCGs) are the most promising energy sources with respect to their current amplification and compactness. They are able of producing high current pulses required in many pulsed power applications with at least one order of magnitude higher energy density than capacitive storage with similar discharge characteristics. However, the main concern with MFCGs is their intrinsic flux loss that limits severely their performance and which is not yet well understood. In general, all flux losses have a differing degree of impact, depending on the generator's volume, current and energy amplification, size of the driven load, and angular frequency of armature-helix contact point. Although several computer models have been developed in the open literature, none of them truly quantify, starting from basic physics principles, the ohmic and intrinsic flux losses in helical MFCGs. This paper describes a novel method that provides a separate calculation of intrinsic flux losses (flux that is left behind in the conductors and lost for compression) and ohmic losses, being especially easy to implement and fast to calculate. We also provide a second method that uses a simple flux quantification, making a mathematical connection between the intrinsic flux losses, quantified by the first method, and the intrinsic flux losses observed in the generators. This second method can also be used to a priori estimate the MFCG performance. Further, we will show experimental and calculated data and discuss the physical efficiency limits and scaling of generator performance at small sizes.

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Publication Year:  2003
+ A Completely Explosive Pulsed Power Mini-System
  "A Completely Explosive Pulsed Power Mini-System", Review of Scientific Instruments, 74, # 1, p 225-230, 2003, (with E.F. Talantsev, S.I. Shkuratov, and J. Dickens).
Abstract:  Not Available
+ Autonomous Ultra-Compact Explosive-Driven High-Voltage Generator Based on a Transverse Shock Wave Demagnetization of Nd2Fe14B Hard Ferromagnetics
  "Autonomous Ultra-Compact Explosive-Driven High-Voltage Generator Based on a Transverse Shock Wave Demagnetization of Nd2Fe14B Hard Ferromagnetics", Review of Scientific Instruments, 74, no. 1, Part 225-230, 2003 (with S.I. Shkuratov, E.F. Talantsev, and J.C. Dickens).
Abstract:  Not Available
+ Currents produced by explosive driven transverse shock wave ferromagnetic source of primary power in a coaxial single-turn seeding coil of a Magnetocumulative generator
  "Currents produced by explosive driven transverse shock wave ferromagnetic source of primary power in a coaxial single-turn seeding coil of a Magnetocumulative generator", Journal of Applied Physics, 93, 4529-4535, 15 April 2003 with Sergey I Shkuratov, Evgueni F. Talantsev and James C. Dickens).
Abstract:  Not Available
+ Efficiency results from a coaxial vircator using a simple feedback technique
  Mankowski, J.; Cheng, X.; Dickens, J.; Kritiansen, M.; Choi, E.; Digest of Technical Papers. PPC-2003. 14th IEEE International Pulsed Power Conference, 2003. Volume 1, 15-18 June 2003 Page(s):455 - 458 Vol.1
Abstract:  Experimental findings on the coaxial virtual cathode oscillator (vircator) at Texas Tech University are reported. A major modification to the system extended the pulse forming line several meters. The pulsed power system now delivers up to 750 kV and 60 kA for at least 70 nsec. Additional modifications include diagnostics to measure the diode voltage, current, and radiated field pattern of the output microwaves. In this initial phase of experiments copper reflectors were installed within the diode to provide a simple means of microwave feedback to assist in the e-beam modulation. Thus far we have observed microwave peak power output with feedback reflectors as high as 3.5 GW corresponding to an efficiency of /spl sim/9.5%. Measured radiated field patterns show evidence of multimode operation.

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+ Helical MFCG For Driving A High Inductance Load
  Andreas A. Neuber, Juan-Carlos Hernández, James C. Dickens, Magne Kristiansen, Electromagnetic Phenomena, vol. 3, pp. 397-404, (2003).
Abstract:  Even at small dimensions of less than 0.5 meter in length end-initiated helical magnetic flux compression generators (MFCG) have at least one order of magnitude higher energy density (by weight or volume) than capacitive energy storage with similar discharge time characteristics. However, simple MFCGs with a single helix produce high output energy only into low inductance loads, thus producing several 100 kA of current at a voltage level of less than 10 kV. Many pulsed power devices require less current but a considerably higher voltage level. For effectively driving a high inductance load of several μH, a multistage MFCG design has been suggested. We successfully tested a dual stage MFCG with a total length of 250 mm, a helix inner diameter of 51 mm, which is wound with Teflon insulated stranded wire of different sizes in the range from AWG 12 to AWG 22. We have presently achieved an energy gain of ~ 13 into a 3 μH load and will discuss the generator performance based on experimental current/voltage waveforms and specify the observed losses.

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+ Longitudinal Shock Wave Demagnetization of High Energy Nd2Fe14B Ferromagnetics
  "Longitudinal Shock Wave Demagnetization of High Energy Nd2Fe14B Ferromagnetics", Applied Physics Letters, 82 8, p.1248-1250, 2003, (with S.I. Shkuratov, E.F. Talantsev, and J.C. Dickens).
Abstract:  Not Available
+ Seed Currents Produced by an Ultracompact Explosive Driven Transverse Shock Wave Ferromagnetic Source of Primary Power in a Seeding Coil of a Magnetocumulative Generator
  "Seed Currents Produced by an Ultracompact Explosive Driven Transverse Shock Wave Ferromagnetic Source of Primary Power in a Seeding Coil of a Magnetocumulative Generator", Applied Physics Letters, 82, 1248-1250, 2003 (with S.I. Shkuratov, E.F. Talantsev, and J.C. Dickens).
Abstract:  Not Available
Publication Year:  2002
+ Compact Explosive-Driven Generator of Primary Power Based on a Longitudinal Shock Wave Demagnetization of Hard Ferri- and Ferromagnetics
  "Compact Explosive-Driven Generator of Primary Power Based on a Longitudinal Shock Wave Demagnetization of Hard Ferri- and Ferromagnetics", IEEE Transactions on Plasma Science Special Issue on Pulsed Power Science and Technology, November 2002, (with S.I. Shkuratov, J.C. Dickens, and J.C. Hernendez).
Abstract:  Not Available
+ Current Mode of Pulsed Power Generation in Moving Magnet Systems
  "Current Mode of Pulsed Power Generation in Moving Magnet Systems", IEEE Transactions on Plasma Science Special Issue on Pulsed Power Science and Technology, November 2002, (with S. Shkuratov, J.C. Dickens, and J.C. Hernandez).
Abstract:  Not Available
+ Gas breakdown in the subnanosecond regime with voltages below 15 kV
  Krompholz, H.; Hatfield, L.L.; Kristiansen, M.; Hemmert, D.; Short, B.; Mankowski, J.; Brown, M.D.J.; Altgilbers, L.L.; IEEE Transactions on Plasma Science, Volume 30, Issue 5, Part 1, Oct. 2002 Page(s):1916 - 1921
Abstract:  Gaseous breakdown in the subnanosecond regime is of interest for fast pulsed power switching, short pulse electromagnetics, and for plasma limiters to protect electronic devices from high power microwave radiation. Previous investigations of subnanosecond breakdown were mainly limited to high-pressure gases or liquids, with voltages in excess of 100 kV. In this paper, we investigate subnanosecond breakdown at applied voltages below 7.5 kV in point-plane geometries in argon, with a needle radius <0.5 /spl mu/m. The coaxial setup allows current and voltage measurements with temporal resolutions down to 80 ps. Voltages of 7.5 kV (which are doubled at the open gap before breakdown) produce breakdowns with a delay of about 1 ns. With negative pulses applied to the tip and the same amplitude, breakdown is always observed during the rising part of the pulse, with breakdown delay times below 800 ps, at pressures between 10/sup 2/ and 10/sup 4/ Pa. At lower pressure, a longer delay time (8 ns at 6 Pa) is observed. We expect the breakdown mechanism to be dominated by electron field emission, but still influenced by gaseous amplification.

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+ High-speed optical diagnostic of an exploding wire fuse
  Giesselmann, M.; Heeren, T.; Neuber, A.; Walter, J.; Kristiansen, M.; IEEE Transactions on Plasma Science, Volume 30, Issue 1, Part 1, Feb. 2002 Page(s):100 - 101
Abstract:  Explosive flux compression generators generate hundreds of kiloamperes and voltages of a few kilovolts. A power conditioning stage is required since typically voltages in the hundreds of kilovolts range are needed. Inductive energy storage systems with an opening switch provide the necessary voltage gain. In our application, the opening switch has been implemented as an exploding wire fuse. The voltage gain, and hence the performance of the system, is greatly dependent on the opening switch. We utilized high-speed optical imaging (up to 107 pictures/s) to assess the performance of the exploding wire fuse

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+ High-speed optical diagnostic of an exploding wire fuse
  M Giesselmann, T Heeren, A Neuber, J Walter, M Kristiansen, "High-speed optical diagnostic of an exploding wire fuse" Plasma Science, IEEE Transactions on 30 (1), 100-101
Abstract:  Not Available
+ Shock Wave Demagnetization of BaFe12O19 Hard Ferrimagnetics
  "Shock Wave Demagnetization of BaFe12O19 Hard Ferrimagnetics", Journal of Applied Physics 91 (2002) 3007-3009 (with S.I. Shkuratov, E.F. Talantsev and J. Dickens.
Abstract:  Not Available
+ Single Shot, Repetitive and Life-Time High-Voltage Testing of Capacitors
  "Single Shot, Repetitive and Life-Time High-Voltage Testing of Capacitors", IEEE Transactions on Plasma Science Special Issue on Pulsed Power Science and Technology, 30 1665, October 2002, (with S.I. Shkuratov, E.F. Talantsev, L.L. Hatfield, and J.C. Dickens).
Abstract:  Not Available
+ Subnanosecond corona inception in an ultrawideband environment
  Mankowski, J.; Dickens, J.; Kristiansen, M.; Lehr, J.; Prather, W.; Gaudet, J.; IEEE Transactions on Plasma Science, Volume 30, Issue 3, Part 1, June 2002 Page(s):1211 - 1214
Abstract:  Corona discharges in ultrawideband radiating systems can have adverse effects on performance such as reflection, phase dispersion, and significant power losses. A test-bed has been assembled to experimentally observe corona created by voltage pulses similar to ultrawideband systems. The current work involves the attenuation of an incident pulse after propagation through a self-initiated corona and relative measurements of visible light emission from the photoionization produced during streamer development. Several gas dielectrics, including ambient air, N/sub 2/, H/sub 2/, and SF/sub 6/, were tested.

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+ The Conductivity of a Longitudinal-Shock-Wave-Compressed Nd2Fe14B Hard Ferromagnetics
  "The Conductivity of a Longitudinal-Shock-Wave-Compressed Nd2Fe14B Hard Ferromagnetics", Modern Physics Letters B, 16, No. 12 (2002) 1-11 (with E.F. Talantsev, S.I. Shkuratov, and J. Dickens).
Abstract:  Not Available
+ Theoretical Treatment of Explosive Driven Ferroelectric Generators
  "Theoretical Treatment of Explosive Driven Ferroelectric Generators", IEEE Transactions on Plasma Science Special Issue on Pulsed Power Science and Technology, 30 1665, October 2002, (with S.I. Shkuratov, Ya. Tkach, E.F. Talantsev, J. Dickens, L.L. Altgilbers, and P.T. Tracy).
Abstract:  Not Available
+ Thermodynamic state of the magnetic flux compression generator volume
  Neuber, A.; Holt, T.; Dickens, J.C.; Kristiansen, M.; IEEE Transactions on Plasma Science, Volume 30, Issue 5, Part 1, Oct. 2002 Page(s):1659 - 1664
Abstract:  The thermodynamic state of the gas trapped in the volume of helical magnetic flux compression generators was measured using optical emission spectroscopy and fast pressure probes. Three main stages of operation are discussed: (1) the initial stage, which can be represented by a freely expanding armature, that shows fairly low gas temperatures, as low as 2000 K; (2) the intermediate stage during 14-4 /spl mu/s before generator burnout that exhibits mainly an atomic copper line transition at about 0.8 eV; (3) the last few /spl mu/s that reveal a highly compressed gas with temperatures of about 5000 K and pressures of about 1500 bar. Most experiments were conducted in air, initially at STP, some results are given for argon and sulfur hexafluoride initially at one atmosphere. Additionally, the thermodynamic state is linked to the electrical volume breakdown threshold via simple resistance measurements that were conducted in current-free flux compression generators.

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+ Transverse Shock Wave Demagnetization of Nd2Fe14B High-Energy Hard Ferromagnetics
  "Transverse Shock Wave Demagnetization of Nd2Fe14B High-Energy Hard Ferromagnetics", Journal of Applied Physics 92 (2002) 159-162 (with S.I. Shkuratov, E.F. Talantsev, and J. Dickens).
Abstract:  Not Available
+ Ultracompact Explosive-Driven High-Current Source of Primary Power Badsed on Shock Wave Demagnetization of Nd2Fe14B Hard Ferromagnetics
  "Ultracompact Explosive-Driven High-Current Source of Primary Power Badsed on Shock Wave Demagnetization of Nd2Fe14B Hard Ferromagnetics", Review of Scientific Instruments, 73 (2002) 2738-2742 (with S.I. Shkuratov, E.F. Talantsev, and J. Dickens).
Abstract:  Not Available
+ Vacuum ultraviolet luminous efficiency and plama ion density in alternating current plasma display panels
  "Vacuum ultraviolet luminous efficiency and plama ion density in alternating current plasma display panels", Applied Physics Letters, 81, 3341-3343, 28 October, 2002 (with Eun Ha Choi, Jenon Chulol Ahn, Min Wug Moon, Yoon Jung, Myung Chul Choi, Yoonho Seo, Guangsup Cho, Han Sup Uhm, Kunihide Tachibana, and Ki Woong Whang).
Abstract:  Not Available
Publication Year:  2001
+ Advanced modeling of an exploding flux compression generator using lumped element models of magnetic diffusion
  M Giesselmann, T Heeren, A Neuber, M Kristiansen, "Advanced modeling of an exploding flux compression generator using lumped element models of magnetic diffusion" Pulsed Power Plasma Science, 2001. PPPS-2001. Digest of Technical Papers 1 162-165
Abstract:  Not Available
+ Calculation of air temperature and pressure history during the operation of a flux compression generator
  X Le, J Rasty, A Neuber, J Dickens, M Kristiansen, "Calculation of air temperature and pressure history during the operation of a flux compression generator" Pulsed Power Plasma Science, 2001. PPPS-2001. Digest of Technical Papers 2 (2) 939-942
Abstract:  Not Available
+ Compact design of a 30 kV rapid capacitor charger
  M Giesselmann, M Kristiansen, "Compact design of a 30 kV rapid capacitor charger" Pulsed Power Plasma Science, 2001. PPPS-20001. Digest of Technical Papers 1 640-643
Abstract:  Not Available
+ Electrical behavior of a simple helical flux compression generator for code benchmarking
  Neuber, A.; Dickens, J.; Cornette, J.B.; Jamison, K.; Parkinson, E.R.; Giesselmann, M.; Worsey, P.; Baird, J.; Schmidt, M.; Kristiansen, M.; IEEE Transactions on Plasma Science, Volume 29, Issue 4, Aug. 2001 Page(s):573 - 581
Abstract:  A variety of basic magnetic flux compression (MFC) generator geometries have been tested during the last three decades. Though size and operating regimes differ widely, it is apparent that the helical flux compression generator is the most promising concept with respect to current amplification and compactness. Though the geometry of the helical generator (dynamically expanding armature in the center of a current carrying helix) seems to be basic, it turns out that the understanding of all involved processes is rather difficult. This fact is apparent from the present lack of a computer model that is solely based on physical principles and manages without heuristic factors. A simple generator was designed to address flux and current losses of the helical generator. The generator's maximum current amplitude is given as a function of the seed current and the resulting “seed-current” spread is compared to the output of state-of-the-art computer models. Temporally resolved current and current time derivative signals are compared as well. The detailed generator geometry is introduced in order to facilitate future computer code bench marking or development. The impact of this research on the present understanding of magnetic flux losses in helical MFC generators is briefly discussed

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+ High speed optical diagnostics of an exploding wire fuse for power conditioning of explosive flux compression generators
  M Giesselmann, T Heeren, A Neuber, J Walter, M Kristiansen, "High speed optical diagnostics of an exploding wire fuse for power conditioning of explosive flux compression generators" Pulsed Power Plasma Science, 2001. PPPS-2001. Digest of Technical Papers 1 (1) 102-105
Abstract:  Not Available
+ Pulsed Power Systems
  "Pulsed Power Systems"”, Encyclopedia of Physical Science and Technology, Third Edition edited by Robert A. Meyers, Vol. 13 (2001), Academic Press, Inc., San Diego, CA (with James C. Dickens).
Abstract:  Not Available
+ Studies on a Helical Magnetic Flux Compression Generator
  A. Neuber, J. Dickens, M. Giesselmann, M. Kristiansen, B. Freeman, D. Dorsey, P. Worsey, J. Baird, M. Schmidt, “Studies on a Helical Magnetic Flux Compression Generator”, Paper 2000-01-3617, Journal of Aerospace, SAE 2000 Transactions, Section 1, ISBN 0-7680-0840-9, © 2001, p. 865…869.
Abstract:  Not Available
+ Theory of the virtual cathode oscillator
  "Theory of the virtual cathode oscillator", Physics of Plasmas, 8, #8, Aug 2001 (with Weihua Jiang).
Abstract:  Not Available
Publication Year:  2000
+ A review of short pulse generator technology
  Mankowski, J.; Kristiansen, M.; IEEE Transactions on Plasma Science, Volume 28, Issue 1, Feb. 2000 Page(s):102 - 108
Abstract:  Today's ultrafast, pulse generators are capable of producing high-voltage pulses, (>1 kV), with fast, leading-edge rise times, (<1 ns). A review of generator implementation methods is presented that includes a detailed discussion of the various circuit designs and a list of commercially available high-voltage pulse generators. All of these generators are capable of rise times less than a few ns and voltages greater than several hundred volts. Finally, a brief description of the three primary switch types, reed, spark gap, and solid state is presented

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+ Dielectric/Gas Interface Breakdown Caused by High Power Microwaves
  D. Hemmert, A. Neuber, H. Krompholz, L.L Hatfield, and M. Kristiansen: Dielectric/Gas Interface Breakdown Caused by High Power Microwaves. Proceedings of the 13th International Conference on High-Power Particle Beams, June 25-30, 2000, Nagaoka, Japan, invited.
Abstract:  Not Available
+ Experimental and analytical investigation of a pulsed power conditioning system for magnetic flux compression generators
  M Giesselmann, T Heeren, E Kristiansen, JG Kim, JC Dickens, M Kristiansen, "Experimental and analytical investigation of a pulsed power conditioning system for magnetic flux compression generators" Plasma Science, IEEE Transactions on 28 (5), 1368-1376
Abstract:  Not Available
+ Experimental and Analytical Investigation of a Pulsed Power Conditioning System for Magnetic Flux Compression Generators
  M. Giesselmann, T. Heeren, E. Kristiansen, J. Kim, J. Dickens, M. Kristiansen, “Experimental and Analytical Investigation of a Pulsed Power Conditioning System for Magnetic Flux Compression Generators”, IEEE Transactions on Plasma Science, October 2000, p. 1368…1376.
Abstract:  Not Available
+ High Current and High Voltage Pulsed Testing of Resistors
  "High Current and High Voltage Pulsed Testing of Resistors", IEEE Transactions on Plasma Science, Special Issue on Pulsed Power Science and Technology, 28 1607-1614, Oct. 2000 (with S.I. Shkuratov, J. Dickens, L.L. Hatfield, and E. Horrocks).
Abstract:  Not Available
+ High-power microwave window breakdown under vacuum and atmospheric conditions
  D Hemmert, AA Neuber, JC Dickens, H Krompholz, LL Hatfield, M Kristiansen, "High-power microwave window breakdown under vacuum and atmospheric conditions" Proceedings of SPIE 4031, 90
Abstract:  Not Available
+ Microwave magnetic field effects on high-power microwave window breakdown
  Hemmert, D.; Neuber, A.A.; Dickens, J.; Krompholz, H.; Hatfield, L.L.; Kristiansen, M.; IEEE Transactions on Plasma Science, Volume 28, Issue 3, June 2000 Page(s):472 - 477
Abstract:  Microwave window breakdown in vacuum is investigated for an idealized geometry, where a dielectric slab is located in the center of a rectangular waveguide with its normal parallel to the microwave direction of propagation. An S-band resonant ring with a frequency of 2.85 GHz and a power of 60 MW is used. With field enhancement tips at the edges of the dielectric slab, the threshold power for breakdown is observed to be dependent on the direction of the microwaves; i.e., it is approximately 20% higher for the downstream side of the slab than it is for the upstream side. Simple trajectory calculations of secondary electrons in an RF field show a significant forward motion of electrons parallel to the direction of microwave propagation. Electrons participating in a saturated secondary avalanche on the upstream side are driven into the surface, and electrons on the downstream side are driven off the surface, because of the influence of the microwave magnetic field. In agreement with the standard model of dielectric surface flashover for dc conditions (saturated avalanche and electron-induced outgassing), the corresponding change in the surface charge density is expected to be proportional to the applied breakdown threshold electric field parallel to the surface

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+ Optical diagnostics on helical flux compression generators
  Neuber, A.A.; Dickens, J.C.; Krompholz, H.; Schmidt, M.F.C.; Baird, J.; Worsey, P.N.; Kristiansen, M.; IEEE Transactions on Plasma Science, Volume 28, Issue 5, Oct. 2000 Page(s):1445 - 1450
Abstract:  Explosively driven magnetic flux compression (MFC) has been object of research for more than three decades. Actual interest in the basic physical picture of flux compression has been heightened by a newly started Department of Defense (DoD) Multi-University Research Initiative. The emphasis is on helical flux compression generators comprising a hollow cylindrical metal liner filled with high explosives and at least one helical coil surrounding the liner. After the application of a seed current, magnetic flux is trapped and high current is generated by moving, i.e., expanding, the liner explosively along the winding of the helical coil. Several key factors involved in the temporal development can be addresses by optical diagnostics. 1) The uniformity of liner expansion is captured by framing camera photography and supplemented by laser illuminated high spatial and temporal resolution imaging. Also, X-ray flash photography is insensitive to possible image blur by shockwaves coming from the exploding liner. 2) The thermodynamic state of the shocked gas is assessed by spatially and temporally resolved emission spectroscopy. 3) The moving liner-coil contact point is a possible source of high electric losses and is preferentially monitored also by emission spectroscopy. Since optical access to the region between liner and coil is not always guaranteed, optical fibers can he used to extract light from the generator. The information so gained will give, together with detailed electrical diagnostics, more insight in the physical loss mechanisms involved in MFC

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+ Pulsed Power Generation Using Ferromagnetic Circuits
  "Pulsed Power Generation Using Ferromagnetic Circuits", IEEE Transactions on Plasma Science, Special Issue on Pulsed Power Science and Technology, 28 1347-1352, Oct. 2000 (with S.I. Shkuratov, J. Dickens, L.L. Hatfield, and R. Martin).
Abstract:  Not Available
+ Studies on a helical magnetic flux compression generator
  A Neuber, J Dickens, M Giesselmann, M Kristiansen, B Freeman, D Dorsey, P Worsey, J Baird, M Schmidt, "Studies on a helical magnetic flux compression generator" SAE Transactions 109 (1), 865-869
Abstract:  Not Available
+ The role of outgassing in surface flashover under vacuum
  Neuber, A.A.; Butcher, M.; Krompholz, H.; Hatfield, L.L.; Kristiansen, M.; IEEE Transactions on Plasma Science, Volume 28, Issue 5, Oct. 2000 Page(s):1593 - 1598
Abstract:  Results of high-speed electrical and optical diagnostics are used as a basis to discuss a new surface flashover model. Outgassing, caused by electron stimulated desorption, is found to play a crucial role in the temporal flashover development. Dielectric unipolar surface flashover under vacuum is experimentally characterized by a three-phase development, which covers a current range from 10-4 A to 100 A. Phase one comprises a fast (several nanoseconds) buildup of a saturated secondary electron avalanche reaching current levels of 10 to 100 mA. Phase two is associated with a slow current amplification reaching currents in the Ampere level within typically 100 ns. The final phase is characterized by a fast current rise up to the impedance-limited current on the order of 100 A. The development during phase two and three is described by a zero-dimensional model, where electron-induced outgassing leads to a Townsend-like gas discharge above the surface. This is supported by time-resolved spectroscopy that reveals the existence of excited atomic hydrogen and ionic carbon before the final phase. The feedback mechanism toward a self-sustained discharge is due to space charge leading to an enhanced field emission from the cathode. A priori unknown model parameters, such as outgassing rate and gas density buildup above the surface, are determined by fitting calculated results to experimental data. The significance of outgassing is also discussed with a view to microwave surface flashover

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Publication Year:  1999
+ Dielectric surface flashover in vacuum at 100 K
  Neuber, A.; Butcher, M.; Hatfield, L.L.; Kristiansen, M.; Krompholz, H.; IEEE Transactions on Dielectrics and Electrical Insulation, [see also IEEE Transactions on Electrical Insulation], Volume 6, Issue 4, Aug. 1999 Page(s):512 - 515
Abstract:  Cryogenic components in high power electrical systems and in power electronics gain more and more importance. The behavior of insulators for cryogenic conditions, however, is virtually unknown. In a fast coaxial setup, dielectric test sample and electrodes in vacuum are cooled to <100 K and flashover is characterized using fast electrical and optical diagnostics. Three consecutive development stages for flashover in self-breakdown mode with a gap distance of 0.5 cm can be distinguished: (1) a fast current rise to mA amplitudes within ~2 ns, probably associated with field emission, followed by, (2) a slow current rise to ~5 to 10 A amplitude with duration of 40 ns to 1 μs, associated with secondary emission avalanche saturation, and (3) a transition to a rapid gaseous ionization above the sample caused by electron induced outgassing, leading to impedance-limited current amplitudes of ⩽300 A. Phase (1) shows a higher final current at lower temperature, which is probably due to a higher initial velocity of the secondary electrons, the duration of phase (2) is a decreasing function of breakdown voltage and only slightly dependent on temperature, which points to a weak temperature dependence of the outgassing process. Flashover potentials show a slight increase at lower temperature

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+ Dielectric surface flashover in vacuum at 100 K
  A Neuber, M Butcher, LL Hatfield, M Kristiansen, H Krompholz, "Dielectric surface flashover in vacuum at 100 K" Dielectrics and Electrical Insulation, IEEE Transactions on 6 (4), 512-515
Abstract:  Not Available
+ Efficiency Enhancement of Coaxial Virtual Cathode Oscillator
  "Efficiency Enhancement of Coaxial Virtual Cathode Oscillator", 27 1543 (1999) IEEE Transaction Plasma Science, (with W. Jiang and J. Dickens).
Abstract:  Not Available
+ High Power Microwave Generation by a Coaxial Virtual Cathode Oscillator
  "High Power Microwave Generation by a Coaxial Virtual Cathode Oscillator", IEEE Transactions on Plasma Science, 27 1538 (1999) (with W. Jiang, K. Woolverton, and J. Dickens).
Abstract:  Not Available
+ Imaging of high-power microwave-induced surface flashover
  Neuber, A.; Hemmert, D.; Dickens, J.; Krompholz, H.; Hatfield, L.L.; Kristiansen, M.; IEEE Transactions on Plasma Science, Volume 27, Issue 1, Feb. 1999 Page(s):138 - 139
Abstract:  Using two gated intensified digital charge-coupled device cameras, one sensitive in the near infrared to ultraviolet region and one in the soft X-ray region, the temporal development of high-power microwave-induced surface flashover across a vacuum/dielectric interface has been imaged. The emission of X-ray radiation from the interface is caused by field emitted electrons accelerated in the high electromagnetic field impacting the solid. This generation of bremsstrahlung terminates at the moment of full flashover development that is indicated by the optical light emission. A rising plasma density above the dielectric surface due to electron induced outgassing triggers this behavior

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+ Initiation of High Power Microwave Dielectric Interface Breakdown
  A. Neuber, D. Hemmert, H. Krompholz, L. Hatfield, and M. Kristiansen: Initiation of High Power Microwave Dielectric Interface Breakdown. J. Appl. Phys., vol. 86, 1724-1728 (1999).
Abstract:  Not Available
Publication Year:  1998
+ High voltage subnanosecond breakdown
  Mankowski, J.; Dickens, J.; Kristiansen, M.; IEEE Transactions on Plasma Science, Volume 26, Issue 3, June 1998 Page(s):874 - 881
Abstract:  Present-day ultra-wideband radiation sources produce Megavolt pulses at hundreds of picosecond (ps) risetimes. Empirical data on the breakdown characteristics for dielectric media at these short time lengths and high voltages are either extremely limited or nonexistent. In support of the design of these ultra-wideband sources, we are investigating the breakdown characteristics, at these voltages and time lengths, of several liquids and high-pressure gases. These include air, N2, H2, SF6, and transformer oil. Gap voltages attained were over 700 kV and gas pressures were over 150 atm (15 MPa). Breakdown times achieved were on the order of 600 ps. Electric field strengths observed for given breakdown times were higher than predicted by other investigators. An empirical fit is presented for the data obtained

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+ Window breakdown caused by high-power microwaves
  Neuber, A.; Dickens, J.; Hemmert, D.; Krompholz, H.; Hatfield, L.L.; Kristiansen, M.; IEEE Transactions on Plasma Science, Volume 26, Issue 3, June 1998 Page(s):296 -
Abstract:  Physical mechanisms leading to microwave breakdown on windows are investigated for power levels on the order of 100 MW at 2.85 GHz. The test stand uses a 3-MW magnetron coupled to an S-band traveling wave resonator. Various configurations of dielectric windows are investigated. In a standard pillbox geometry with a pressure of less than 10-6 Pa, surface discharges on an alumina window and multipactor-like discharges starting at the waveguide edges occur simultaneously. To clarify physical mechanisms, window breakdown with purely tangential electrical microwave fields is investigated for special geometries. Diagnostics include the measurement of incident/reflected power, measurement of local microwave fields, discharge luminosity, and X-ray emission. All quantities are recorded with 0.21-ns resolution. In addition, a framing camera with gating times of 5 ns is used. The breakdown processes for the case with a purely tangential electric field is similar to DC flashover across insulators, and similar methods to increase the flashover field are expected to be applicable

[PDF]

Publication Year:  1997
+ Arc Erosion Behavior of Cu-15% Nb and Cu-15% Cr in Situ Composites”, Elsevier
  "Arc Erosion Behavior of Cu-15% Nb and Cu-15% Cr in Situ Composites”, Elsevier", Wear: an International Journal on Science and Technology of Friction and Wear” 36 (1997) (with P. Liu, S. Bahadur (Univ. Of Iowa) and Anthony L. Donaldson).
Abstract:  Not Available
+ Dielectric Surface Flashover in a Simulated Low Earth Orbit Environment
  F. Hegeler, H. Krompholz, L.L. Hatfield, M. Kristiansen, “Dielectric Surface Flashover in a Simulated Low Earth Orbit Environment”, IEEE Transactions on Plasma Science, 25 (1997) 300
Abstract:  Not Available
+ Electrical and Optical Characterization of Crystalline Silicon/Porous Silicon Hetero-junctions
  "Electrical and Optical Characterization of Crystalline Silicon/Porous Silicon Hetero-junctions", Solar Energy Materials and Solar Cells, 46, 261 (1997) (with C. Palsule, S. Liu, S. Gangopadhyay, M. Holtz, and D. Lamp).
Abstract:  Not Available
Publication Year:  1995
+ Review of the Mechanisms of Electrode and Insulator Erosion and Degradation in High Current Arc Environments
  "Review of the Mechanisms of Electrode and Insulator Erosion and Degradation in High Current Arc Environments", IEEE Transactions on Magnetics, 31, 709, (1995) (with T.G. Engel, S.L. Wester, and A.L. Donaldson).
Abstract:  Not Available
Publication Year:  1994
+ Electron-Beam Controlled Switching Using Quartz and Polycrystalline ZnSe
  "Electron-Beam Controlled Switching Using Quartz and Polycrystalline ZnSe", IEEE Transactions on Electron Devices, 41, 582 (1994) (with W. Jiang, K. Zinsmeyer, M. Less, and K.H. Schoenbach).
Abstract:  Not Available
Publication Year:  1993
+ Insulator and Electrode Mass Erosion and Surface Voltage Holdoff Recovery for Transient, High Current Surface Discharges
  "Insulator and Electrode Mass Erosion and Surface Voltage Holdoff Recovery for Transient, High Current Surface Discharges", IEEE Transactions on Magnetics, 29, 1143 (1993) (with T.G. Engel and J.C. Dickens).
Abstract:  Not Available
Publication Year:  1992
+ Magnetic field effects on vacuum insulator flashover
  M. Lehr, R. Korzekwa, H. Krompholz, M. Kristiansen, "Magnetic field effects on vacuum insulator flashover", J. Appl. Phys. 71 (1992) 389
Abstract:  Not Available
Publication Year:  1991
+ Estimating the Erosion and Degradation Performance of Ceramic and Polymeric Insulator Materials in High Current Arc Environments
  "Estimating the Erosion and Degradation Performance of Ceramic and Polymeric Insulator Materials in High Current Arc Environments", IEEE Transactions on Magnetics, 27, 533, (1991) (with T.G. Engel, E. O'Hair, and J.N. Marx).
Abstract:  Not Available
+ Expansion of Hydrogen Arcs Driven by Oscillating Currents
  T.G. Engel, M. Kristiansen, H. Krompholz, "Expansion of Hydrogen Arcs Driven by Oscillating Currents", IEEE Transactions on Plasma Science 19 (1991) 959
Abstract:  Not Available
+ Picosecond Time-Resolved Photoluminescence Characterization of a-SiC:H Films Prepared by Electron Cyclotron Resonance Plasma
  "Picosecond Time-Resolved Photoluminescence Characterization of a-SiC:H Films Prepared by Electron Cyclotron Resonance Plasma", J. Non-Cryst. Solids, 137 and 138, 859 (1991) (with S. Gangopadhyay, M. Pleil, W. Borst, and C. Young).
Abstract:  Not Available
+ Plasma Diagnostics for High Power Ignitron Development
  D.L. Loree, M. Giesselmann, M. Kristiansen and A. Shulski, "Plasma Diagnostics for High Power Ignitron Development", IEEE Transactions on Magnetics, Vol. 27, No.1, January 1991.
Abstract:  Not Available
+ Surface-Discharge Switch Design: The Critical Factor
  "Surface-Discharge Switch Design: The Critical Factor", IEEE Trans. Electron Devices, 38, 740, (1991) (with T.G. Engel, M.C. Baker, and L.L. Hatfield).
Abstract:  Not Available
+ The Design and Calibration of a Very Fast Current Probe for Short Pulse Measurements
  S. Calico, M. Crawford, M. Kristiansen, H. Krompholz, "The Design and Calibration of a Very Fast Current Probe for Short Pulse Measurements", Rev. Sci. Instrum 62 (1991) 1511
Abstract:  Not Available
Publication Year:  1990
+ On the Road to Tomsk
  "On the Road to Tomsk", Physics Today, June 1990, 36 (with A.H. Guenther and J.E. Thompson) also translated to Japanese, Physical Science Magazine, Dec. 1990.
Abstract:  Not Available
+ The Influence of Magnetic Fields on Dielectric Surface Flashover
  R. Korzekwa, M. Lehr, H. Krompholz, M. Kristiansen, "The Influence of Magnetic Fields on Dielectric Surface Flashover", IEEE Transactions on Electron Devices, 38 (1990) 745
Abstract:  Not Available
+ Voltage-Current Characteristics of a High-Current Pulsed Discharge in SF6
  "Voltage-Current Characteristics of a High-Current Pulsed Discharge in SF6", (in Japanese), Denki Gakkai Ronbunshi, 110-B, No. 7, 560, (1990)(with Hidenori Akiyama, Tetsuro Tanigawa, Sadao Maeda, and Koichi Takaki), also translated to English in Scripta Technica. (See #102.)
Abstract:  Not Available
+ Voltage-Current Characteristics of High-Current Pulsed Discharges in SF6, Electrical Engineering in Japan
  "Voltage-Current Characteristics of High-Current Pulsed Discharges in SF6, Electrical Engineering in Japan", 111, No. 3 July 1991 (translated from Denki Gakkai Ronbunshi, 110B, No. 7, July 1990, 560-567 (with Hidenori Akiyama, Tetsuro Tanigawa, Sadao Maeda and Koichi Takaki). (Also see #92.)
Abstract:  Not Available
Publication Year:  1989
+ Design Options for Optically Restructuring Damaged Image Detectors
  "Design Options for Optically Restructuring Damaged Image Detectors", SPIE/ Optical Engineering, 28, 854 (1989) (with E.A. Igel).
Abstract:  Not Available
+ Electrode Erosion from High Current Moving Arcs
  "Electrode Erosion from High Current Moving Arcs", IEEE Trans. on Plasms Science, PS-17, 811 (1989) (with F. Mark Lehr).
Abstract:  Not Available
+ Inhibiting Surface Flashover for Space Conditions Using Magnetic Fields
  R. Korzekwa, M. Lehr, H. Krompholz, M. Kristiansen, "Inhibiting Surface Flashover for Space Conditions Using Magnetic Fields", IEEE Trans. on Plasma Science, 17 (1989) 612
Abstract:  Not Available
+ Methods of Increasing the Surface Flashover Potential in Vacuum
  L.L. Hatfield, E.R. Boerwinkle, G. Leiker, H. Krompholz, R. Korzekwa, M. Lehr, M. Kristiansen, "Methods of Increasing the Surface Flashover Potential in Vacuum", IEEE Trans. on Electrical Insulation, 24 (1989) 985
Abstract:  Not Available
+ State-of-the-Art Insulator and Electrode Materials for Use in High Current, High Energy Switching
  "State-of-the-Art Insulator and Electrode Materials for Use in High Current, High Energy Switching", IEEE Trans. on Magnetics, MAG-25, 138 (1989) (with A.L. Donaldson and T.G. Engel).
Abstract:  Not Available
+ The Performance of New, Redesigned Ignitron Tubes in Axial Magnetic Fields
  D. Adkins, M. Giesselmann, and M. Kristiansen, "The Performance of New, Redesigned Ignitron Tubes in Axial Magnetic Fields", IEEE Transactions on Magnetics, Vol. 25, No. 1, January 1989, p. 27...32.
Abstract:  Not Available
+ The Pulsed Discharge Arc Resistance and Its Functional Behavior
  "The Pulsed Discharge Arc Resistance and Its Functional Behavior", IEEE Trans. on Plasma Science, PS-17, 323 (1989) (with T.G. Engel and A.L. Donaldson).
Abstract:  Not Available
+ Warm Plasma Dispersion Relation of the Fast Alfven Wave for Asymmetrical Heating Current Drive
  "Warm Plasma Dispersion Relation of the Fast Alfven Wave for Asymmetrical Heating Current Drive", IEEE Trans. Plasma Science, PS-17, 520 (1989) (with J. Gahl, O. Ishihara, and M. Hagler).
Abstract:  Not Available
Publication Year:  1988
+ Analytical and Experimental Investigations of Reed Contact Bouncing
  "Analytical and Experimental Investigations of Reed Contact Bouncing", IEEE Trans. on Components, Hybrids, and Manufacturing Technology" CHMT-11, 200 (1988) (with B. Miedzinski).
Abstract:  Not Available
+ CO2-Laser Enhanced Electron Attachment in Externally Sustained Diffuse Gas Discharges Containing Vinyl Chloride
  G. Schaefer, M. Giesselmann, B. Pashaie, and M. Kristiansen, "CO2-Laser Enhanced Electron Attachment in Externally Sustained Diffuse Gas Discharges Containing Vinyl Chloride", Journal of Applied Physics 64 (11), 1 December 1988, p. 6123...6127.
Abstract:  Not Available
+ Optimization of Gas Mixtures for Electron Beam Controlled Diffuse Discharge Opening Switches
  "Optimization of Gas Mixtures for Electron Beam Controlled Diffuse Discharge Opening Switches", J. Appl. Phys., 63, 1372 (1988) (with R. Korzekwa and G. Schaefer).
Abstract:  Not Available
Publication Year:  1987
+ Fast Alfven Wave Propagation in a Deuterium-Hydrogen Tokamak Plasma
  "Fast Alfven Wave Propagation in a Deuterium-Hydrogen Tokamak Plasma," Plasma Phys. and Controlled Fusion, 29, 93 (1987) (with H. Akiyama, K.L. Wong, J. Gahl and M. Hagler).
Abstract:  Not Available
+ Numerical Studies of Minority Ion Heating Current Drive
  "Numerical Studies of Minority Ion Heating Current Drive," Phys. Fluids, 30, 834 (1987) (with K.L. Wong, O. Ishihara, J. Gahl and M. Hagler).
Abstract:  Not Available
+ Observation of Local Cavity Resonances of Fast Alfven Waves
  "Observation of Local Cavity Resonances of Fast Alfven Waves," Nuclear Fusion, 27, 151 (1987)(with K.L. Wong, M. Hagler, O. Ishihara and H. Akiyama).
Abstract:  Not Available
+ Pulsed Power Systems": Encyclopedia of Physical Science and Technology
  "Pulsed Power Systems": Encyclopedia of Physical Science and Technology, 11, 410 (1987), Academic Press, Inc., San Diego, CA (with M.O. Hagler).
Abstract:  Not Available
Publication Year:  1986
+ Analytical Studies of an Ablation Mass Driver System
  "Analytical Studies of an Ablation Mass Driver System," J. Appl. Phys., 59, 3397 (1986) (with K. Ikuta and M.F. Rose).
Abstract:  Not Available
+ Charging of Insulators in a Surface Discharge Switch
  "Charging of Insulators in a Surface Discharge Switch," IEEE Trans. Elec. Insulation EI-21, 145 (1986) (with R.D. Curry, V.K. Agarwal, L.L. Hatfield and G.R. Leiker).
Abstract:  Not Available
+ Conical Linear Implosion as a Projectile Injector for Mass Drivers
  "Conical Linear Implosion as a Projectile Injector for Mass Drivers," Japanese J. Appl. Phys. 25, L198 (1986) (with K. Ikuta).
Abstract:  Not Available
+ Electrode Erosion in High Current, High Energy Transient Arcs
  "Electrode Erosion in High Current, High Energy Transient Arcs," IEEE Trans. Mag., MAG-22, 1441 (1986) (with A.L. Donaldson, A. Watson, K. Zinsmeyer, E. Kristiansen, and Rolf Dethlefsen).
Abstract:  Not Available
+ Experimental Observation of Current Generation by Asymmetrical Heating of Ions in a Tokamak Plasma
  "Experimental Observation of Current Generation by Asymmetrical Heating of Ions in a Tokamak Plasma," J. Appl. Physics 60, 4322 (1986) (with J. Gahl, O. Ishihara, K.L. Wong and M. Hagler).
Abstract:  Not Available
+ Insulator Damage in High Current Discharges
  "Insulator Damage in High Current Discharges," IEEE Trans. Mag., MAG-22, 1695 (1986) (with P.M. Ranon, F.M. Lehr and L.L. Hatfield).
Abstract:  Not Available
+ Mechanism of Electrode Surface Damage and Material Removal in High Current Discharges
  "Mechanism of Electrode Surface Damage and Material Removal in High Current Discharges," IEEE Trans. Mag., MAG-22, 1799 (1986) (with A. Watson, A.L. Donaldson and K. Ikuta).
Abstract:  Not Available
+ Reliability Assurance in Electromagnetic Launch Technology
  "Reliability Assurance in Electromagnetic Launch Technology," IEEE Trans. Mag., MAG-22, 1567 (1986) (with W.J. Kolarik and T.L. Landers).
Abstract:  Not Available
+ The Influence of the Circuit Impedance on an Electron-Beam Controlled Diffuse Discharge with a Negative Differential Conductivity
  "The Influence of the Circuit Impedance on an Electron-Beam Controlled Diffuse Discharge with a Negative Differential Conductivity," Appl. Phys. Lett. 48, 1776 (1986) (with G. Schaefer, K.H. Schoenbach, B.E. Strickland, R.A. Korzekwa and G.Z. Hutcheson).
Abstract:  Not Available
Publication Year:  1985
+ An Electron Beam Controlled Diffuse Discharge Switch
  K. Schoenbach, G. Schaefer, M. Kristiansen, H. Krompholz, H. Harjes, D. Skaggs, "An Electron Beam Controlled Diffuse Discharge Switch", J. Appl. Phys. 57 (1985) 1618
Abstract:  Not Available
+ Antenna for Unidirectional Propagation of Fast Alfven Waves in a Tokamak
  "Antenna for Unidirectional Propagation of Fast Alfven Waves in a Tokamak," Rev. Sci. Instrum. 56, 1151 (1985) (with H. Akiyama, J. Gahl, K. Rathbun and M. Hagler).
Abstract:  Not Available
+ Modeling of Self-Breakdown Voltage Statistics in High Energy Spark Gaps
  "Modeling of Self-Breakdown Voltage Statistics in High Energy Spark Gaps," J. Appl. Phys. 57, 4981 (1985) (with A.L. Donaldson and M.O. Hagler).
Abstract:  Not Available
+ Wall Effects on the Propagation of Compressional Alfven Waves in a Cylindrical Plasma with Two Ion Species
  "Wall Effects on the Propagation of Compressional Alfven Waves in a Cylindrical Plasma with Two Ion Species," IEEE Trans. Plasma Sci. PS-13, 125 (1985) (with H. Akiyama and M.O. Hagler).
Abstract:  Not Available
Publication Year:  1984
+ A Review of Opening Switch Technology for Inductive Energy Storage
  "A Review of Opening Switch Technology for Inductive Energy Storage," Proc. IEEE 72, 1019 (1984) (with K.H. Schoenbach and G. Schaefer).
Abstract:  Not Available
+ Electrode Erosion Phenomena in a High Energy Pulsed Discharge
  "Electrode Erosion Phenomena in a High Energy Pulsed Discharge," IEEE Trans. Plasma Sci. PS-12, 28 (1984) (with A. Donaldson, M. Hagler, G. Jackson and L. Hatfield).
Abstract:  Not Available
+ Electron Beam Tetrode for Multiple, Submicrosecond Pulse Operation
  H. Harjes, K. Schoenbach, G. Schaefer, M. Kristiansen, H. Krompholz, D. Skaggs, "Electron Beam Tetrode for Multiple, Submicrosecond Pulse Operation", Rev. Sci. Instrum. 55 (1984) 1684
Abstract:  Not Available
+ Investigations of E-Beam Controlled Diffuse Discharges
  K. Schoenbach, G. Schaefer, M. Kristiansen, H. Krompholz, H. Harjes, D. Skaggs, "Investigations of E-Beam Controlled Diffuse Discharges" in "Gaseous Dielectrics IV", ed. L. G. Christophorou, Pergamon Press 1984, p. 246
Abstract:  Not Available
+ Nanosecond Current Probe for High Voltage Experiments
  H. Krompholz, J. Doggett, K. Schoenbach, J. Gahl, C. Harjes, G. Schaefer, M. Kristiansen, "Nanosecond Current Probe for High Voltage Experiments", Rev. Sci. Instrum. 55 (1984) 127
Abstract:  Not Available
+ Surface Studies of Dielectric Materials Used in Spark Gaps
  "Surface Studies of Dielectric Materials Used in Spark Gaps," J. Appl. Phys. 55, 262 (1984) (with G. Jackson, L. Hatfield, M. Hagler, J. Marx, A. Donald­son, G. Leiker, R. Curry, R. Ness, L. Gordon and D. Johnson).
Abstract:  Not Available
+ The Use of Attachers in Electron-Beam Sustained Discharge Switches - Theoretical Considerations
  G. Schaefer, K. Schoenbach, H. Krompholz, M. Kristiansen, A.H. Guenther, "The Use of Attachers in Electron-Beam Sustained Discharge Switches - Theoretical Considerations", Laser and Particle Beams 2 (1984) 273
Abstract:  Not Available
Publication Year:  1983
+ Pulse Flashover of Solid Dielectrics in Vacuum
  "Pulse Flashover of Solid Dielectrics in Vacuum," IEEE Trans. Elect. Insul. EI-18, 310 (1983) (with G. Jackson, L. Hatfield, J. Marx and A. Bowling).
Abstract:  Not Available
Publication Year:  1982
+ Concepts for Optical Control of Diffuse Discharge Opening Switches
  "Concepts for Optical Control of Diffuse Discharge Opening Switches," IEEE Trans. Plasma Sci. PS-10, 246 (1982) (with K.H. Schoenbach, G. Schaefer, L.L. Hatfield and A.H. Guenther).
Abstract:  Not Available
+ Guest Editorial
  Guest Editorial, IEEE Trans. Plasma Sci. PS-10, 217 (1982) (with A.H. Guenther, M.F. Rose, and J.E. Thompson).
Abstract:  Not Available
+ Investigations of Reed Switch Dynamics and Discharge Phenomena When Switching Intermediate and Heavy Loads
  "Investigations of Reed Switch Dynamics and Discharge Phenomena When Switching Intermediate and Heavy Loads," IEEE Trans. Components, Hybrids and Manu­facturing Techn. CHMT-5, 231 (1982) (with B. Miedzinski).
Abstract:  Not Available
+ Material Studies in a High Energy Spark Gap
  "Material Studies in a High Energy Spark Gap" IEEE Trans. Plasma Sci. PS-10, 286 (1982) (with L.B. Gordon, M.O. Hagler, H.C. Kirbie, R.M. Ness, L.L. Hatfield and J. Marx).
Abstract:  Not Available
+ Space Charge Effects in a Laser-Fiber Optics Triggered Multichannel Spark Gap
  "Space Charge Effects in a Laser-Fiber Optics Triggered Multichannel Spark Gap," IEEE Trans. Plasma Sci. PS-10, 261 (1982) (with H.C. Harjes, E.E. Kunhardt, L.L. Hatfield and A.H. Guenther).
Abstract:  Not Available
+ The Effect of Space Charge Induced by an Electron Beam on Spark Gap Operation
  "The Effect of Space Charge Induced by an Electron Beam on Spark Gap Operation" IEEE Trans. Plasma Sci. PS-10, 234 (1982) (with Y.H. Tzeng, E.E. Kunhardt and A.H. Guenther).
Abstract:  Not Available
Publication Year:  1981
+ Investigations of Various Probe Sheath Materials in the Texas Tech Tokamak
  "Investigations of Various Probe Sheath Materials in the Texas Tech Tokamak," IEEE Trans. Plasma Sci. PS-9, 123 (1981) (with P.D. Coleman, B.D. Blackwell and M.O. Hagler).
Abstract:  Not Available
Publication Year:  1980
+ An Electron Beam Triggered Spark Gap
  "An Electron Beam Triggered Spark Gap," IEEE Trans. Plasma Sci. PS-8, 181 1980) (with K. McDonald, M. Newton, E. Kunhardt and A.H. Guenther).
Abstract:  Not Available
+ Basic Concepts in Electromagnetic Theory
  "Basic Concepts in Electromagnetic Theory", Acad. Amer. Ency., Arete Publ. Co., Princeton, NJ (1980) (with A. Engelhardt).
Abstract:  Not Available
+ Electro-Optical Surface Flashover Measurement
  "Electro-Optical Surface Flashover Measurement," Appl. Phys. Lett. 37, 574 (1980) (with J.E. Thompson, J. Lin and K. Mikkelson).
Abstract:  Not Available
+ Guest Editorial
  Guest Editorial, IEEE Trans. Plasma Sci. PS-8, 129 (1980) (with A.H. Guenther).
Abstract:  Not Available
+ Investigations of Fast Insulator Surface Flashover in Vacuum
  "Investigations of Fast Insulator Surface Flashover in Vacuum," IEEE Trans. Plasma Sci. PS-8, 191 (1980) (with J.E. Thompson, J. Lin and K. Mikkelson).
Abstract:  Not Available
+ Laser Triggering through Fiber Optics of a Low Jitter Spark Gap
  "Laser Triggering through Fiber Optics of a Low Jitter Spark Gap," IEEE Trans. Plasma Sci. PS-8, 170 (1980) (with H.C. Harjes, L. Hatfield, K.H. Schoenbach and A.H. Guenther).
Abstract:  Not Available
Publication Year:  1979
+ A New Nanosecond Surface Flashover Diagnostic Technique
  "A New Nanosecond Surface Flashover Diagnostic Technique," J. Japan Res. Soc. for Elec. Discharges (JRED), No. 78, 73 (1979).
Abstract:  Not Available
+ A Review of High Power Switch Technology
  "A Review of High Power Switch Technology," IEEE Trans. Electron Devices ED-26, 1401 (1979) (with T.R. Burkes, J.P. Craig, M.O. Hagler and W.M. Portnoy).
Abstract:  Not Available
+ Beat Heating in Plasmas Using CO2 Lasers
  "Beat Heating in Plasmas Using CO2 Lasers," J. de Physique, Colloque C7, suppl. 7, 40, C7-747 (1979) (with E. Chu, R. Druce, M. Hagler and R. Bengtson).
Abstract:  Not Available
+ Electro-Optical Measurements of Insulator Surface Flashover in Vacuum
  "Electro-Optical Measurements of Insulator Surface Flashover in Vacuum," J. de Physique, Colloque C7, suppl. 7, 40, C7-401 (1979) (with K. Mikkelson, J. Lin and J. Thompson).
Abstract:  Not Available
+ Fast Wave Resonances Near the Ion Cyclotron Frequency
  "Fast Wave Resonances Near the Ion Cyclotron Frequency," IEEE Trans. Plasma Sci. PS-7, 1 (1979) (with R.E. Dollinger and M.O. Hagler).
Abstract:  Not Available
+ Laser/Fiber Optic Breakdown of a Pulse Charged 90% Ar - 10% N2 Gas Switch
  "Laser/Fiber Optic Breakdown of a Pulse Charged 90% Ar - 10% N2 Gas Switch," J. de Physique, Colloque C7, suppl. 7, 40, C7-483 (1979) (with H.C. Harjes, L.L. Hatfield, A.H. Guenther and K.H. Schoenbach).
Abstract:  Not Available
Publication Year:  1977
+ A Numerical Analysis of High Power Laser Propagation in Magnetized Plasmas
  "A Numerical Analysis of High Power Laser Propagation in Magnetized Plasmas," Recent Advances in Plasma Phys., Indian Acad. of Sci., 165, June 1977 (with R. Druce and M.O. Hagler).
Abstract:  Not Available
+ Ablation Rates of Polystyrene Microspheres in a Theta Pinch Plasma
  "Ablation Rates of Polystyrene Microspheres in a Theta Pinch Plasma," J. Appl. Phys. 46, 11 (1977) (with D.L. Smith and M.O. Hagler).
Abstract:  Not Available
Publication Year:  1976
+ Laser Heating of Magnetized Plasma
  "Laser Heating of Magnetized Plasma," Nucl. Fusion 16, 6 (1976) (invited review paper) (with M.O. Hagler).
Abstract:  Not Available
+ Optical Measurements of High Electric and Magnetic Fields
  "Optical Measurements of High Electric and Magnetic Fields," IEEE Trans. Instr. and Meas. IM-25, 1 (1976) (with J.E. Thompson and M.O. Hagler).
Abstract:  Not Available
Publication Year:  1975
+ Differential Measurement of Fast Energy Discharge Capacitor Inductance and Resistance
  "Differential Measurement of Fast Energy Discharge Capacitor Inductance and Resistance," IEEE Trans. Instr. and Meas. IM-24, 112 (1975) (with W.C. Nunnally and M.O. Hagler).
Abstract:  Not Available
+ Helical Antenna for Exciting Azimuthally Asymmetric Alfven Waves
  "Helical Antenna for Exciting Azimuthally Asymmetric Alfven Waves," J. Appl. Phys. 46, 2516 (1975) (with S.O. Knox and F.J. Paoloni).
Abstract:  Not Available
+ Plasma-Solid Interaction in a Theta Pinch
  "Plasma-Solid Interaction in a Theta Pinch," Appl. Phys. Lett. 26, 496 (1975) (with W.C. Nunnally and M.O. Hagler).
Abstract:  Not Available
Publication Year:  1974
+ A Report on the Second Topical Conference on RF Plasma Heating
  "A Report on the Second Topical Conference on RF Plasma Heating," Nucl. Fusion 14, 741 (1974) (with F.J. Paoloni).
Abstract:  Not Available
+ CO2 Laser Heating of a Magnetized Plasma Column
  "CO2 Laser Heating of a Magnetized Plasma Column," Appl Phys. Lett. 24, 583 (1974) (with G.M. Molen, M.O. Hagler and R.D. Bengtson).
Abstract:  Not Available
+ Simple, Multiple Arc, Dielectric Switch Applied to a Theta Pinch
  "Simple, Multiple Arc, Dielectric Switch Applied to a Theta Pinch," Rev. Sci. Inst. 45, 1361 (1974) (with W.C. Nunnally and M.O. Hagler).
Abstract:  Not Available
Publication Year:  1973
+ A Report on the Texas Symposium on the Technology of Controlled Thermonuclear Fusion Experiments and the Engineering Aspects of Fusion Reactors
  "A Report on the Texas Symposium on the Technology of Controlled Thermonuclear Fusion Experiments and the Engineering Aspects of Fusion Reactors," Nucl. Fusion 13, 281 (1973).
Abstract:  Not Available
+ CO2 Laser Beam Refraction in a Linear Discharge Plasma
  "CO2 Laser Beam Refraction in a Linear Discharge Plasma," Appl. Phys. Lett. 23, 601 (1973) (with G.M. Molen and M.O. Hagler).
Abstract:  Not Available
+ Exploding Wires in Strong Axial Magnetic Fields
  "Exploding Wires in Strong Axial Magnetic Fields," J. Appl. Phys. 44, 1923 (1973) (with E.M. Honig and M.O. Hagler).
Abstract:  Not Available
Publication Year:  1972
+ A Holographic Data Storage System Design Project
  "A Holographic Data Storage System Design Project," Int. J. Elec. Engrg. Educ. 10, 296 (1972) (with R.M. David, C.R. Parten and M.O. Hagler).
Abstract:  Not Available
+ An Azimuthally Symmetric, Unidirectional Ion Cyclotron Wave Exciter
  "An Azimuthally Symmetric, Unidirectional Ion Cyclotron Wave Exciter," J. Appl. Phys. 43, 3590 (1972) (with J.E. Hipp and M.O. Hagler).
Abstract:  Not Available
+ CO2 Laser Design and Laboratory Projects
  "CO2 Laser Design and Laboratory Projects," IEEE Trans. Educ. E-15, 51 (1972) (with G.M. Molen, R.H. Trotter and M.O. Hagler).
Abstract:  Not Available
+ Fast Wave Damping at the Second Harmonic of the Ion Cyclotron Frequency
  "Fast Wave Damping at the Second Harmonic of the Ion Cyclotron Frequency," Phys. Lett. A40, 141 (1972) (with J.E. Cato, M.O. Hagler and C.N. Watson­-Munro).
Abstract:  Not Available
+ Some Engineering Problems of Low Frequency Heating of Fusion Reactors
  "Some Engineering Problems of Low Frequency Heating of Fusion Reactors," Nucl. Fusion 12, 345 (1972) (with J.E. Cato and M.O. Hagler).
Abstract:  Not Available
Publication Year:  1971
+ Fusion Reactor Design, Nuclear Power: The 1970's
  "Fusion Reactor Design, Nuclear Power: The 1970's," Professional Engineer 41, 2, Feb. 1971 (with M.O. Hagler).
Abstract:  Not Available
+ Global Temperature Effects of the Use of Fusion Energy and the Fusion Torch
  "Global Temperature Effects of the Use of Fusion Energy and the Fusion Torch," IEEE Trans. Nucl. Sci. 18, 31 (1971), (with W.A. Porter and M.O. Hagler).
Abstract:  Not Available
+ Heat Shrinkable Tubing as an Inexpensive Vacuum Seal
  "Heat Shrinkable Tubing as an Inexpensive Vacuum Seal," J. Vacuum Sci. and Techn. 8, 515 (1971) (with G.M. Molen, L.G. Roseland and M.O. Hagler).
Abstract:  Not Available
+ Travelling Wave Antenna for Exciting Waves in Cylindrical Anisotropic Plasma
  "Travelling Wave Antenna for Exciting Waves in Cylindrical Anisotropic Plasma," J. Appl. Phys. 42, 4887 (1971) (with M.O. Hagler and J.E. Hipp).
Abstract:  Not Available
Publication Year:  1970
+ An Optical Data Processing Experiment for E.E. Students
  "An Optical Data Processing Experiment for E.E. Students," IEEE Trans. Educ. E-13, 60 (1970) (with L.N. Peckham and M.O. Hagler).
Abstract:  Not Available
+ Arc Welding Generators Used as Air Core Magnet Power Supplies
  "Arc Welding Generators Used as Air Core Magnet Power Supplies," Rev. Sci. Instr. 41, 1322 (1970) (with J.E. Cato, J.E. Hipp and M.O. Hagler).
Abstract:  Not Available
+ Industrial Applications of Lasers
  "Industrial Applications of Lasers," ISA Trans. 9, 216 (1970) (with L.N. Peckham and M.O. Hagler).
Abstract:  Not Available
+ Inexpensive, Fast On-Off, High Power, Pulsed RF Amplifier
  "Inexpensive, Fast On-Off, High Power, Pulsed RF Amplifier," Rev. Sci. Instr. 41, 1903 (1970) (with R.D. Melton, J.E. Cato and M.O. Hagler).
Abstract:  Not Available
+ Laser Laboratory Projects for Undergraduates
  "Laser Laboratory Projects for Undergraduates," Engrg. Educ. 60, 899, (1970) (with L.N. Peckham and M.O. Hagler)
Abstract:  Not Available
Publication Year:  1969
+ Foreign Students in American Universities
  "Foreign Students in American Universities," Engrg. Educ. 59, 1135 (1969).
Abstract:  Not Available
+ Stop- and Pass-Bands for Harmonic Ion Cyclotron Waves
  "Stop- and Pass-Bands for Harmonic Ion Cyclotron Waves," Plasma Phys. 11, 19 (1969) (with A.A. Dougal).
Abstract:  Not Available
+ The Use of Hamilton's Modified Principle to Solve Nonlinear Control Problems
  "The Use of Hamilton's Modified Principle to Solve Nonlinear Control Problems," ISA Trans. 8, 329 (1969) (with M.O. Hagler and L.G. Clark).
Abstract:  Not Available
Publication Year:  1967
+ Experimental Investigation of Harmonic Ion Cyclotron Wave Propagation and Attenuation
  "Experimental Investigation of Harmonic Ion Cyclotron Wave Propagation and Attenuation," Phys. Fluids 10, 596 (1967) (with A.A. Dougal).
Abstract:  Not Available
+ Inexpensive, High Vacuum, Electric Feed-Through
  "Inexpensive, High Vacuum, Electric Feed-Through," Rev. Sci. Instr. 38, 840 (1967) (with J.G. Melton and A.A. Dougal).
Abstract:  Not Available
Publication Year:  1966
+ Evaluation of Faraday-Shielded Stix Coils for Ion Cyclotron Resonance Heating of a Plasma
  "Evaluation of Faraday-Shielded Stix Coils for Ion Cyclotron Resonance Heating of a Plasma," Rev. Sci. Instr. 37, 1455 (1966) (with N.B. Dodge and A.A. Dougal).
Abstract:  Not Available
Publication Year:  1963
+ Hamilton's Modified Principle Applied to Nonlinear Circuit Problems
  "Hamilton's Modified Principle Applied to Nonlinear Circuit Problems," IEEE Trans. Comm. and Circuit Theory 69, 598 (1963) (with L.G. Clark).
Abstract:  Not Available

Conference Paper/Presentation

Publication Year:  2011
+ Compact Electro-Explosive Fuse Optimization for a Helical Flux Compression Generator
  J. C. Stephens, A. A. Neuber, J. C. Dickens, M. Kristiansen, "Compact Electro-Explosive Fuse Optimization for a Helical Flux Compression Generator," to be published in Proceedings of the 18th IEEE International Pulsed Power Conference, June 19th - 23rd, Chicago, IL (2011)
Abstract:  This paper presents the optimization of a compact electro-explosive fuse designed for the power conditioning system to be driven by a helical flux compression generator (HFCG). An electro-explosive fuse interrupts the current flow from the HFCG through a storage inductor on a 50 to 100 ns timescale inducing a voltage large enough to close a peaking gap, which commutates the energy in the storage inductor into a 20 Ohm load at voltage levels above 200 kV. Experimental data has revealed that electro-explosive fuses with wires in closer proximity to one another have consistently produced lower pulsed voltages than fuses with larger wire spacings. This paper addresses possible factors that might contribute to this drop in performance. An electro-magnetic field solver is used to model the current redistribution in the fuse wires. The experimentally observed performance of compact fuses with varying wire spacings is presented.

[PDF]

+ COMSED 2 - Recent Advances to an Explosively Driven High Power Microwave Pulsed Power System
  M. A. Elsayed, A. A. Neuber, A. J. Young, J. W. Walter, C. S. Anderson, S. L. Holt, J. R. Korn, M. Kristiansen, "COMSED 2 - Recent Advances to an Explosively Driven High Power Microwave Pulsed Power System," to be published in Proceedings of the 18th IEEE International Pulsed Power Conference, June 19th - 23rd, Chicago, IL
Abstract:  Continued efforts at the Center for Pulsed Power and Power Electronics at Texas Tech University have led to improvements to the design, testing, and performance of a high power microwave (HPM) system, which is sourced by Lithium-ion Polymer batteries, a polypropylene capacitor, and high energetics. An indirectly seeded two-stage helical flux compression generator (HFCG) produces electrical energies in the kilo-Joule regime into a low impedance inductive load, varying from 2 μH to 3 μH. This high current output of the explosively driven generator is conditioned with a pure silver-wire-based electro-explosive opening switch, which reaches voltage levels in excess of 300 kV into a 18 Ohm load. Upon reaching levels high enough to close an integrated peaking switch, this high voltage is sufficient to drive a reflex triode virtual cathode oscillator, also known as a Vircator, into radiation. The Vircator employed in the system has reached microwave radiation levels well over 100 Megawatts from a cavity volume of less than 5 Liters at a microwave frequency of a few GHz. The complete system is governed through a microcontroller that regulates seed and detonator charging levels as well as discharge times using built-in feedback diagnostics. The complete system aforementioned is constrained to 15 centimeter diameter and measures 183 centimeter in length with an overall volume of less than 34 Liters. No external power or vacuum pumping for the HPM tube is required. This report will discuss recent design advancements and improvements on the HPM system and its sub-components that include the compact seed source, HFCG, and the power conditioning system. Improved safety features implemented as well as novel diagnostic integration will be discussed as well.

[PDF]

+ Diagnostic Measurements on Explosive Emission Cathodes Operating at High Current Densities and UHV Pressures
  C. F. Lynn, J. Walter, A. Neuber, M. Kristiansen, "Diagnostic Measurements on Explosive Emission Cathodes Operating at High Current Densities and UHV Pressures," to be published in Proceedings of the 18th IEEE International Pulsed Power Conference, June 19th - 23rd, Chicago, IL (2011)
Abstract:  Not Available
+ Improvements to a Small Scale Linear Transformer Driver
  D. W. Bolyard, A. Neuber, J. Krile, M. Kristiansen, "Improvements to a Small Scale Linear Transformer Driver," to be published in Proceedings of the 18th IEEE International Pulsed Power Conference, June 19th - 23rd, Chicago, IL (2011)
Abstract:  A linear transformer driver (LTD) is being constructed at Texas Tech University's Center for Pulsed Power and Power Electronics with the goal to achieve roughly 100 ns pulse width into an 18 Ohm load and energy densities similar to or greater than a previously designed and built 500 J compact Marx generator. A single experimental LTD stage, previously constructed, tested, and reported on by TTU, has undergone several improvements as well as the inclusion of additional diagnostics. Testing at a charging voltage of 14 kV into a 1.7 Ω resistive load has experimentally achieved a 10% to 90% risetime of ~60 ns, peak voltage of 9.2 kV, peak current of 5.5 kA, and instantaneous power of 50.6 MW. Simulations of the LTD stage correlate closely with the experimental results. Extrapolating the simulations to the final desired charging voltage indicate peak voltages and peak currents exceeding 15 kV and 10 kA respectively, with instantaneous power greater than 150 MW from a single LTD stage. The design for a multi-stage LTD using magnetic cores with a flux swing of 6 kV-μs will be presented. Improvements in diagnostics and modeling of the LTD will also be discussed as well.

[PDF]

+ Initial Anode Optimization for a Compact Sealed Tube Vircator
  J. Walter, J. Vara, C. Lynn, J. Dickens, A. Neuber, M. Kristiansen, "Anode Optimization for a Compact Sealed Tube Vircator," to be published in Proceedings of the 18th IEEE International Pulsed Power Conference, June 19th - 23rd, Chicago, IL (2011)
Abstract:  During the development and optimization of a compact sealed tube virtual cathode oscillator (vircator) at Texas Tech University, it has become apparent that processes at the anode have a significant impact on tube performance. The impact of the high energy, high current density (100-200 A/cm2 or higher) beam on the anode will cause outgassing, plasma production, and anode melting and material ejection. The emitted material expands, eventually impacting the anode transparency and (combined with the plasma formed at the cathode) shorting out the anode-cathode gap. This expansion limits the maximum radiated pulse width, and can also limit the peak output power. The residual evolved gas also negatively impacts the maximum repetition rate of the tube. An effort is underway to study the thermal behavior, gases evolved, and transparency versus time for different vircator anode materials and material treatments. Several different anode materials are under investigation, including stainless steel, copper tungsten, tantalum, nickel, and molybdenum. The effect of different treatments on the anodes before tube assembly is also being studied. The gases that are evolved during operation have been characterized utilizing pressure and residual gas analyzer measurements. The pre-shot background pressure in the tube is in the ultra-high vacuum range (10-8 to 10-9 Torr), and the vircator is not pumped on during firing. The data collected for the different materials is presented.

[PDF]

Publication Year:  2010
+ A Low Impedance 500 kV 2.75 kJ Marx Generator as Testbed for Vacuum Diodes
  C. Lynn, A. Neuber, E. Matthews, J. Walter, M. Kristiansen, "A Low Impedance 500 kV 2.75 kJ Marx Generator as Testbed for Vacuum Diodes," 2010 IEEE International Power Modulator and High Voltage Conference, May 23 - 27, 2010 in Atlanta, GA.
Abstract:  A low impedance Marx generator was developed as part of a test bed for vacuum diodes of various electrode materials and geometries. The generator supplies sufficient energy to initiate and sustain the typically unwanted plasma formation within the diode; which facilitates the observation of the plasma, current uniformity, and electron current densities of various diode structures. The generator consists of ten stages; each stage utilizes a 220 nF 50 kV capacitor, with a series inductance of ~20 nH. When charged to the rated voltage of the capacitors the energy density of the complete generator with case, spark gaps, insulation, etc., is 19.2 mJ/cm3; this is roughly the energy density of a typical ceramic doorknob capacitor without any supporting structure or isolation. The energy density of the capacitors utilized in the Marx generator by themselves is 104 mJ/cm3. Fired into a low inductance short, the ringing frequency was measured to be 1.4 MHz resulting in an output impedance of 5.2 Ω. Erection of the Marx required adding forward feeding capacitors as the stray capacitance to ground is smaller than the capacitance (~60 pF) of the low inductance, low profile spark gap switches. The design and construction of this generator are discussed as well as selected experimental results obtained with the generator.

[PDF]

+ Compact Magnetically Insulated Transmission Line Oscillator
  Vasiliy Smirnov, Magne Kristiansen, John Mankowski, James Dickens, Andreas Neuber, Lynn Hatfield, Hermann Krompholz, John Walter, "Compact Magnetically Insulated Transmission Line Oscillator", ICOPS 2010, The 37th IEEE International Conference on Plasma Science, June 20 - 24, 2010, Norfolk, Virginia, USA, Page 251.
Abstract:  Not Available
+ COMSED 1 - A Compact, Gigawatt Class Microwave Source Utilizing Helical Flux Compression Generator Based Pulsed Power
  A. Young, A .Neuber, M. Elsayed, J. Korn, J. Walter, S. Holt, J. Dickens, M. Kristiansen, L. Altgilbers, "COMSED 1 - A Compact, Gigawatt Class Microwave Source Utilizing Helical Flux Compression Generator Based Pulsed Power," 2010 IEEE International Power Modulator and High Voltage Conference, May 23 - 27, 2010 in Atlanta, GA. Invited.
Abstract:  Recent progress in the development of a compact, portable, explosively-driven high power microwave source is presented. The envelope to which the system must fit has a 15 cm diameter, which means each sub-system fits within this dimension, with an optimized overall length. The system includes an autonomous prime energy source, which provides the initial energy for a two-stage, flux-trapping helical flux compression generator (FCG). Typical output from the FCG is several kilojoules into a 3 μH inductor. The amplified energy from the generator, after pulse conditioning, is used to drive a virtual cathode oscillator (vircator). Recorded voltages at the vircator with this arrangement were greater than 200 kV in experiments, where radiated output powers of greater than 100 MW have been measured. Voltages of at least 300 kV, with an electrical output power of 4 GW or greater, were generated by the FCG driven pulsed power source into a water resistor load with an impedance similar to the operating impedance of the vircator. A description of each component of the compact microwave source will be given, along with waveforms from tests performed with the components independent of the rest of the system. Data from experiments with the fully integrated microwave system will be shown, and analysis will be offered to detail the performance of the system in its present state.

[PDF]

+ Effects of Gas Temperature and Gas Mixtures on a Triggered, Sub-ns Jitter, 50 kV, 100 Hz Spark Gap
  Y. Chen, J. Dickens, J. Mankowski, M. Kristiansen, "Effects of Gas Temperature and Gas Mixtures on a Triggered, Sub-ns Jitter, 50 kV, 100 Hz Spark Gap", 2010 IEEE International Power Modulators and High Voltage Conference, Atlanta GA, May 2010.
Abstract:  Recent research efforts at Texas Tech University on impulse antenna phased array have shown that an ideal jitter of a small fraction of the rise-time is required to accurately synchronize the array to steer and preserve the rise-time of the radiated pulse. This has necessitated the need to develop a reliable high voltage, high repetition rate switch that will operate with very low jitter. This manuscript presents the impact gases and gas mixtures have on switch performance which includes recovery rate and in particular jitter. A 50 Ω, 1 nF pulse forming line is charged to 50 kV and provides the low inductance voltage source to test the different gases. Gases tested include N2, dry air, H2, and SF6, as well as N2-H2, N2-SF6, N2-Ar, and gas mixtures containing Kr85. This manuscript will discuss in detail 50 kV, 100 Hz triggered switch operations of such gases. Switch jitter as a result of triggering conditions is also discussed, also including an evaluation of jitter as a function of formative delay in various gases. An evaluation of switch jitter as a function of operation time and gas temperature is also included. Triggering is provided by a solid state opening switch voltage source that supplies ~150 kV, 10 ns rise-time pulses at a rep-rate up to 100 Hz in burst mode. A hermetically sealed spark gap with a Kel-F -PCTFE (PolyCholoroTriFluoroEthylene) lining is used to house the switch and high pressure gas. It is shown that jitter is strongly dependent on the triggering technique, as well as the trigger magnitude, with ionization rates playing an important role. Sub-ns jitter is seen with a variety of gases and gas mixtures with H2 producing the best results. Varying the gas temperature and addition of radioactive sources are seen to improve the switch jitter.

[PDF]

+ First Results of Streamer Formation During Dielectric Surface Flashover at Atmospheric Conditions
  K. Frank, J. Dickens, L. Hatfield, M. Kristiansen, G. Laity, A. Neuber, G. Rogers, "First Results of Streamer Formation During Dielectric Surface Flashover at Atmospheric Conditions," DPG Spring Meeting of the Atoms, Molecules, Optics, and Plasmas Section, March 8th - 12th, Hannover, Germany, (2010).
Abstract:  Not Available
+ Modeling Of Compact Explosively-Driven Ferroelectric Generators
  D. Bolyard, A. Neuber, J. Krile, M. Kristiansen, "Modeling Of Compact Explosively-Driven Ferroelectric Generators," 2010 IEEE International Power Modulator and High Voltage Conference, May 23 - 27, 2010 in Atlanta, GA.
Abstract:  Hydrodynamic pressure simulations combined with an empirical algorithm are used to model the open-circuit voltage output of several explosively compressed ferroelectric materials. The empirical algorithm was initially developed using detonating cord containing PETN and a metal driver element to compress the ferroelectric materials while the open-circuit voltage is recorded. A hydrodynamic code suite, CTH from Sandia National Labs, enables calculating Shockwave propagation and localized pressures. The resulting pressure profile in the ferroelectric material is then used as input for an empirically derived algorithm to calculate the predicted open-circuit voltage of the ferroelectric material. This previously developed empirical algorithm exhibited reasonable correlation between experimental and calculated open-circuit output voltages, but began to deviate when more powerful explosives were used. Hence, the amount of explosive material and geometry of the metal drive was varied to produce a wide range of peak pressures, including pressures higher then the maximum of 3.1 GPa previously modeled by the empirical algorithm. This data serves as the base to further develop the empirical algorithm for various ferroelectric materials and to more accurately model the open-circuit output voltage (experimentally observed range, normalized for thickness, of 1.3 to 3.8 kV/mm) over the wide range of applied pressures.

[PDF]

+ Optimization of a Fuse Opening Switch for a Compact Power Conditioning Unit
  J. Korn, A. Young, A. Neuber, C. Davis, M. Elsayed, M. Kristiansen, L. Altgilbers, "Optimization of a Fuse Opening Switch for a Compact Power Conditioning Unit," 2010 IEEE International Power Modulator and High Voltage Conference, May 23 - 27, 2010 in Atlanta, GA.
Abstract:  The results from an investigation into the performance of a fuse opening switch, to be used as a component of a compact power conditioning unit, PCU, in an explosively driven high power microwave system, is presented. A pulse forming network designed to mimic the current action of a flux compression generator is utilized for these experiments. The investigation focused on the effect of altering fuse parameters, such as the diameter of fuse conductors and conductor winding geometry, on voltage and power levels delivered to a resistive load. Also, experiments were conducted with a thin layer of Semicosil, a commercial silicon material used in slower fusing opening switches, applied to fuse conductors, to investigate the possible advantages of using such a coating. Experiments showed that an increased number of conductor wires (with an approximately constant total cross-sectional area) resulted in similar voltages delivered to the resistive load, and that coating fuse conductors with Semicosil had a negligible effect on power delivery. A detailed description of these experiments will be given, along with data and waveforms illustrating the effects of these parameter variations on power levels delivered to the load.

[PDF]

+ Optimizing Wire Parameters in Exploding Wire Arrays
  C. Davis, A. Neuber, J. Stephens, A. Young, M. Kristiansen, "Optimizing Wire Parameters in Exploding Wire Arrays," 2010 IEEE International Power Modulator and High Voltage Conference, May 23 - 27, 2010 in Atlanta, GA.
Abstract:  Exploding wire arrays as fast switches are of interest for explosive pulsed power applications utilizing magnetic flux compression. This type of opening switch has proven effective in producing pulses of several hundred kilovolts into vacuum diode loads. The research presented here discusses an exploding wire array capable of producing single digit kilo-joules, 100 nanosecond pulses when driven by a 45 kilo-Amp current with a waveform closely resembling typical magnetic flux compression output. For this specific parameter range, the optimal fuse design was developed based on the experimental behavior of the fuse under variation of parameters such as wire spacing, shielding, and quenching medium. Each fuse is composed of several silver wires arranged in a straight wire cylindrical array and is typically pressurized in a chamber filled with about 0.6 MPa of SF6. The tradeoff between wire spacing and voltage output was addressed by designing four different fuse termination pairs each with a diameter that increased wire spacing from 5 to 20 mm in 5 mm increments. A wire shield test was also conducted as an extension to the wire spacing experiment to uncover any mutual radiative effects between wires on fuse opening behavior. The optimum fuse design, including the optimum fuse wire diameter, will be discussed with a 20 Ohm resistive load as well as a vacuum diode load with similar impedance.

[PDF]

+ Performance of a Dual-Stage Helical Flux Compression Generator Under Varying Background Gas And Pressure
  M. Elsayed, A. Neuber, A. Young, J. Korn, J. Dickens, M. Kristiansen, C. Lynn, L. Altgilbers, "Performance of a Dual-Stage Helical Flux Compression Generator Under Varying Background Gas And Pressure," 2010 IEEE International Power Modulator and High Voltage Conference, May 23 - 27, 2010 in Atlanta, GA.
Abstract:  Recent efforts at the Center for Pulsed Power and Power Electronics at Texas Tech University have been focused on the development of a compact and explosively driven High Power Microwave, HPM, system. The primary energy source (other than the seed energy source) driving the microwave load in this system is a mid-sized, dual-stage helical flux compression generator, HFCG. The HFCG has a constant stator inner diameter of 7.6 cm, a length of 26 cm, with a working volume of 890 cm3. Testing at the Center has revealed energy gains in the 30's and 40's with output energy levels in the kilo-joules regime into loads of several micro-Henries. Over the last few years, close to one hundred shots have been taken with these generators into various loads consisting of dummy inductive loads, power conditioning systems, and HPM sources. Throughout these tests, the working volume of the HFCG, i.e. the volume in between the wire stator and the explosive-filled aluminum armature, was filled with SF6 at atmospheric pressure. This was primarily done do avoid electrical breakdown in the generator volume during operation, resulting in flux loss. Recent design updates enable pressurizing the generator volume to pressures up to 0.5 MPa, which is needed, for instance, to replace the SF6 with other gases such as air or nitrogen. The performance of the dual-stage HFCG with pressurized working volume (SF6 and N2) is presented in this paper along with an analysis of the maximum electric field amplitude held off in the volume during operation. The design technique to seal the HFCG will also be briefly discussed.

[PDF]

+ Pulsed Atmospheric Breakdown
  G. Laity, H. Krompholz, A. Neuber, L. Hatfield, K. Frank, A. Fierro, J. Dickens, M. Kristiansen, "Pulsed Atmospheric Breakdown," AFOSR Counter High Power Microwaves Meeting, July 29th - 30th, Albuquerque, NM, (2010).
Abstract:  Not Available
+ Rapid Charging Seed Source with Integrated Fire Set for Flux Compression Generator Applications
  S. L. Holt, M. A. Elsayed, B. Gaston, J. C. Dickens, A. A. Neuber, M. Kristiansen, "Rapid Charging Seed Source with Integrated Fire Set for Flux Compression Generator Applications," 2010 IEEE International Power Modulator and High Voltage Conference, May 23 - 27, 2010 in Atlanta, GA.
Abstract:  The design and testing of an integrated front-end power and control system for helical flux compression generators (HFCG) is presented. A current up to 12 kiloamps needs to be pushed into the 5.8 microhenry field coil of the HFCG to establish the necessary seed flux for generator operation. This current is created with the discharge of a 5 kilovolt, 50 microfarad metalized polypropylene film capacitor using a single-use semiconductor closing switch. Once peak current/flux is obtained in the seed coil an exploding bridge wire (EBW) detonator is initiated with a discharge from a 1 kilovolt, 500 millijoule capacitor array contained in the compact fire set. Both capacitances, seed and fire set, are charged using a rapid capacitor charger system. The rapid capacitor charger is a solid state step up converter supplied by lithium-ion polymer (LiPo) batteries. It provides the 5 kilovolts and 1 kilovolt dual output voltages required for the compact seed source and compact fire set, respectively. The rapid capacitor charger operates at an average output power of 3 kilowatts and charges both capacitances simultaneously in under 250 milliseconds. The rapid capacitor charger is reusable if protected from the explosive detonation.

[PDF]

+ Simulation of Cascaded Flux Compression Generators with Conventional Circuit Simulation Software
  A. Young, A. Neuber, M. Kristiansen, "Simulation of Cascaded Flux Compression Generators with Conventional Circuit Simulation Software," The 13th International Conference on Megagauss Magnetic Field Generation and Related Topics, July 06-10, 2010, Nanlin Hotel, Suzhou, China.
Abstract:  Not Available
+ Synchronization of Phased Array Pulsed Ring-down Sources using a GPS based timing system
  Y. Chen, J. Dickens, S. Holt, D. Reale, J. Mankowski, and M. Kristiansen, "Synchronization of Phased Array Pulsed Ring-down Sources using a GPS based timing system", 2010 IEEE International Power Modulators and High Voltage Conference, Atlanta GA, May 2010.
Abstract:  A collaborative effort at Texas Tech University on high power RF transmitters has directly translated to the development of phased array pulsed ring down sources (PRDS). By operating an array of PRDS, peak radiating power on target can theoretically be multiplied by the number of sources. The primary limitation on the application of the array concept is the jitter with which the individual sources can be fired. An ideal jitter of a small fraction of the risetime is required to accurately synchronize the array to steer and preserve the risetime of the radiated pulse. This paper describes in detail the implementation of a GPS based timing system that will synchronize the individual antennas to operate at different geo-locations to function in a coordinated fashion to deliver the peak power of each element to a single position. Theoretical array performance is shown through Monte Carlo simulations, accounting for switch jitter and a range of GPS timing jitter. Each module will include a control unit, low jitter pulser, low jitter spark gap, antenna element, as well as a GPS receiver. The location of each module is transmitted to a central controller, which calculates and dictates when each element is fired. Low jitter in the timing of the GPS reference signal is essential in synchronizing each element to deliver the maxim power. Testing using a preliminary setup using GPS technology is conducted with both 1 pps and 100 pps outputs. Jitter results between modules are recorded to ~10 ns without any correction factors. With the timing and geospatial errors taken into account, the proposed concept will show usable gains of up to several hundred MHz.

[PDF]

+ Time-Resolved Spectral Investigations of Pulsed Atmospheric Dielectric Surface Flashover Discharges
  K. Frank, G. Laity, A. Neuber, G. Rogers, L. Hatfield, J. Dickens, M. Kristiansen, A. Fierro, "Time-Resolved Spectral Investigations of Pulsed Atmospheric Dielectric Surface Flashover Discharges," 63rd Gaseous Electronics Conference, October 4th - 8th, Paris, France, (2010).
Abstract:  In an attempt to identify the mechanisms leading to pulsed dielectric surface flashover in atmospheric conditions, a surface flashover event occurring on a magnesium fluoride (MgF$_{2})$ window was studied. The electrode configuration and the applied pulsed voltage level were chosen such that the generated electric field was symmetric with respect to the centerline between the electrodes. Sharpened stainless steel electrodes (estimated tip radius of 200$\mu $m) are attached to springs which press down onto the MgF$_{2}$ surface a distance of 8 mm apart. Diagnostics include time resolved emission spectroscopy in the VUV range and gated ICCD optical imaging of streamer progression during the first 30 nanoseconds of breakdown (with 3 nanosecond resolution) in the visible wavelength range. One important parameter on which the streamer formation and the subsequent breakdown strongly depends is the gas type and/or the gas composition. That is why the streamer formation was recorded for gated intervals from 3 to 50 ns in lab air, standard nitrogen, oxygen and SF$_{6}$. The results are compared to those ones in purified air, oxygen and nitrogen.

[PDF]

Publication Year:  2009
+ A 15 kA Linear Transformer Driver
  D. Matia, M. Giesselmann, A. Neuber, M. K. Kristiansen, "A 15 kA Linear Transformer Driver," Proceedings of the 2009 IEEE Pulsed Power Conference (PPC), pp. 926-929, Washington, DC, June 2009.
Abstract:  The design of a 15 kA linear transformer driver (LTD) is presented. The specific goal of this LTD was improved energy density over the 500 J compact Marx generator previously designed and built at Texas Tech's Pulsed Power lab. The design of an individual 50 joule, 30 kV stage is discussed. For successful operation of the LTD, multiple spark gaps have to be fired with low jitter. Possible approaches for the design of a compact, low jitter triggering circuit will be presented as well.

[PDF]

+ Electrical Conduction in Select Polymers under Shock Loading
  C. F. Lynn, A. A. Neuber, J. T. Krile, J. Dickens, M. Kristiansen, "Electrical Conduction in Select Polymers under Shock Loading," Proceedings of the 2009 IEEE Pulsed Power Conference (PPC), pp. 171-174, Washington, DC, June 2009.
Abstract:  It is known that polymers become conductive under shock loading, which can be critical to the operation of explosive driven high current/voltage devices. Hence, the propensity of several select polymers to conduct under shock loading was investigated. Four polymers, Nylon, Teflon, Polypropylene, and High Density Polyethylene, were tested under shock pressures up to ~22 GPa. Shock waves were generated with high explosives, and CTH, a hydrodynamic code developed at Sandia National Laboratories, was utilized to calculate pressure and temporal resolution of the shock waves. Time of arrival measurements of the shock waves were taken to correlate the hydrodynamic calculations with experimental results. A notable delay between shock front arrival and the onset of conduction is exhibited by each polymer. The delay tends to decrease with increasing pressure down to approximately 500 ns for HDPE at ~22 GPa under electric field strength of ~6.3 kV/cm. The data shows that some polymers exhibit more delay than others, thereby indicating better insulating properties under shock loading. Additionally, experiments revealed that the polymers conducted for a finite time on the microsecond time scale before recovering back to an insulating state. This recovery from a shock wave induced conducting state back to insulating state was investigated for a possible opening switch application.

[PDF]

+ Integration of a Self-Contained Compact Seed Source and Trigger Set for Flux Compression Generators
  M. A. Elsayed, A. A. Neuber, M. Kristiansen, L. L. Altgilbers, "Integration of a Self-Contained Compact Seed Source and Trigger Set for Flux Compression Generators," Proceedings of the 2009 IEEE Pulsed Power Conference (PPC), pp. 297-300, Washington, DC, June 2009.
Abstract:  Two integral components that accompany an FCG in an explosively driven system is the prime power source and the trigger set. The objective of the prime power source or seed source is to provide the initial seed current/energy into the primary stage of an FCG. Another integral component in an FCG based pulsed power system is the trigger set. The trigger set is used to detonate an exploding bridge wire (EBW) which triggers the high explosives (HE's) in an FCG. This paper will discuss a recent design of a stand-alone apparatus that implements a self-contained (battery powered with full charge time less than 40 sec), single-use Compact Seed Source (CSS) using solid state components for the switching scheme along with a single-use Compact Trigger Set (CTS) that also implements a similar switching technique. The CSS and CTS stand-alone apparatus developed is a system (0.005-m3 volume and weighing 3.9 kg) capable of delivering over 360-J (~12 kA) into a 5.20-¿H FCG load and approximately 2-mJ (~600 A) into the EBW. Both the CSS and CTS have trigger energies of micro-Joules at the TTL triggering level.

[PDF]

+ Low Jitter Triggered Spark Gap with High Pressure Gas Mixtures and Kr85
  Y.J. Chen, J.C. Dickens, J.W. Walter, M. Kristiansen, "Low Jitter Triggered Spark Gap with High Pressure Gas Mixtures and Kr85," 36th IEEE International Conference on Plasma Science, May 31st - June 5th, San Diego, CA, (2009).
Abstract:  Summary form only given. A recent research effort at Texas Tech University on impulse antenna phased arrays has necessitated the need to develop a reliable high voltage, high repetition rate switch that will operate with ultra low jitter. An ideal jitter of a small fraction of the risetime is required to accurately synchronize the array to steer and preserve the risetime of the radiated pulse. A 50 Omega, 1 nF pulse forming line is charged to 50 kV and provides the low inductance voltage source to test the different gases. Triggering is provided by a solid state opening switch voltage source that supplies ~80 kV, 10 ns risetime pulses at a rep rate up to 100 Hz in burst mode. A hermetically sealed spark gap with a Kel-F lining is used to house the switch and high pressure gas. Previously, the system was successfully tested with 50 kV, 100 Hz switch operations. Gases tested include, dry air, H2, N2, and SF6, as well as H2-N2, and N2-SF6 gas mixtures. A discussion on switch operation time and switch gas temperature vs. jitter will be included in this paper. This paper will also discuss in detail the effects on switch jitter when different concentrations of Kr85 gas are introduced.

[PDF]

+ Power Conditioning Optimization for a Flux Compression Generator Using a Non-Explosive Testing System
  C. B. Davis, A. Young, A. A. Neuber, J. C. Dickens, M. Kristiansen, "Power Conditioning Optimization for a Flux Compression Generator Using a Non-Explosive Testing System," Proceedings of the 2009 IEEE Pulsed Power Conference (PPC), pp. 951-955, Washington, DC, June 2009
Abstract:  Not Available
+ Prediction of Compact Explosively-Driven Ferroelectric Generator Performance
  D. W. Bolyard, A. Neuber, J. Krile, J. Dickens, M. Kristiansen, "Prediction of Compact Explosively-Driven Ferroelectric Generator Performance," Proceedings of the 2009 IEEE Pulsed Power Conference (PPC), pp.167-170, Washington, DC, June 2009
Abstract:  Explosively-driven ferroelectric generators are attractive as potential prime energy sources for one-time use pulsed power systems. While the output voltages of small ferroelectric discs have been shown to be on the order of the theoretical maximum values, scaling the ferroelectric to larger thicknesses has proven less successful. The primary limiting factor is how much of the ferroelectric material is compressed simultaneously. This is difficult to control for thicker ferroelectric discs or stacks of discs due to pressure pulse attenuation in the material and rarefaction waves shortening the pressure pulse. A hydrodynamic code system is utilized to calculate the temporally and spatially resolved pressure. The calculated pressure values are converted into voltage produced by the ferroelectric through an algorithm based on an empirical polarization-pressure hysteresis curve. The validity of the algorithm has been verified for PZT EC-64 with experimental data from a flyer-plate experiment reported in literature and our own experiments with the shock wave from the explosives more directly applied to the ferroelectric. Both calculations and experiments produced normalized output voltages, ranging from 1.4 to 3.4 kV/mm for 2.54 cm diameter discs. We will discuss how this pressure to voltage algorithm along with pressure simulations aided in the scaling of the amount of ferroelectric material in a generator, as well as in the design of new driver elements with the goal to increase the peak output voltage of a generator while keeping the generator compact. The calculated voltage output results are compared with experimental data of explosively-driven ferroelectric generators.

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+ Stand-Alone, FCG-Driven High Power Microwave System
  A. Young, M. Elsayed, J. Walter, A. Neuber, J. Dickens, M. Kristiansen, L. Altgilbers, "Stand-Alone, FCG-Driven High Power Microwave System," Proceedings of the 2009 IEEE Pulsed Power Conference (PPC), pp. 292-296, Washington, DC, June 2009.
Abstract:  An explosively driven High Power Microwave (HPM) source has been developed that is based on the use of a Flux Compression Generator (FCG) as the primary driver. Four main components comprise the HPM system, and include a capacitor-based seed energy source, a dual-staged FCG, a power conditioning unit and an HPM diode (reflex-triode vircator). Volume constraints dictate that the entire system must fit within a tube having a 15 cm diameter, and a length no longer than 1.5 m. Additional design restrictions call for the entire system to be stand-alone (free from any external power sources). Presented here are the details of HPM system, with a description of each subcomponent and its role in the generation of HPM Waveforms will be shown which illustrate the development of power as it commutates through each stage of the system, as well as power radiated from the diode. Analysis and comparisons will be offered that will demonstrate the advantages of an explosively driven HPM system over more conventional pulsed power devices.

[PDF]

+ Vacuum Ultraviolet Spectroscopy of Dielectric Surface Flashover at Atmospheric Pressure
  G. Laity, K. Frank, G. Rogers, M. Kristiansen, J. Dickens, A. Neuber, T. Schramm, "Vacuum Ultraviolet Spectroscopy of Dielectric Surface Flashover at Atmospheric Pressure," 36th International Conference on Plasma Science, May 31st - June 5th, San Diego, CA, (2009).
Abstract:  Summary form only given. Spectroscopic measurements in the vacuum ultraviolet (VUV) regime are difficult to make due to extremely large absorption of VUV radiation in most materials. This paper describes an experimental setup designed for studying the optical emission during pulsed surface flashover for the wavelength range between 115 nm to 300 nm at atmospheric pressures. A vacuum monochromator VM 505 from Acton Research Corporation was used as the spectrograph. For VUV transmission down to 115 nm the light emitted by surface flashover across an MgF2 window (front side of window in air, backside in vacuum) was focused by an MgF2 lens onto the entrance slit of the spectrograph. A quartz window with sodium salicylate coating exposed to the spectrograph's vacuum was placed in the exit focal plane of the collimating mirror of the spectrograph. This fluorescent coating down-converts the VUV light to longer wavelengths that were recorded with an Andor DH520 series ICCD camera in combination with a Nikon 105 mm lens. Spectra were measured at atmospheric pressure with a flashover spark length of about 9 mm and DC excitation with a capacitance of 4.1 nF. Emission spectra were measured from 300 nm down to 130 nm. In parallel, theoretical spectra were calculated primarily for the identification of radiating species and their temperature. Utilizing the NIST Atomic Spectra Database (ASD) data a library of temperature dependent optical emission spectra was generated with SpectraPlot, a spectral software suite developed at TTU. VUV spectral lines of nitrogen, carbon, magnesium and silicon were identified. In pure nitrogen, for instance, the nitrogen I double line at 174.3 nm and 174.5 nm is clearly visible in the spectrum along with a strong double line at 279.6 nm and 280.4 nm, which is emitted by Magnesium II, eroded from the surface exposed to flashover. Spectra were measured in ambient air, pure nitrogen, and argon. An experiment upgrade is currently u- nderway, increasing the VUV sensitivity of the setup. The measured spectra will be discussed in relation to the physics of surface flashover and volume breakdown at atmospheric pressure.

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Publication Year:  2008
+ A 50 kV, 100 Hz Low Jitter Triggered Spark Gap with High Pressure Gas Mixtures
  Chen, Yeong-Jer; Mankowski, John J.; Dickens, James C.; Walter, John; Kristiansen, Magne; A 50 kV, 100 Hz Low Jitter Triggered Spark Gap with High Pressure Gas Mixtures; IEEE International Power Modulators and High Voltage Conference, Proceedings of the 2008; 27-31 May 2008 Page(s):197 - 200; Digital Object Identifier 10.1109/IPMC.2008.4743614
Abstract:  Recent research efforts at Texas Tech University on impulse antenna phased array has necessitated the need to develop a reliable high voltage, high repetition rate switch that will operate with ultra low jitter. An ideal jitter of a small fraction of the risetime is required to accurately synchronize the array to steer and preserve the risetime of the radiated pulse. In (Y. Chen et al., 2007), we showed the initial test system with sub-ns results for operations in different gases and gas mixtures. This paper presents the impact gases and gas mixtures have on switch performance which includes recovery rate and in particular jitter. A 50 Omega, 1 nF pulse forming line is charged to 50 kV and provides the low inductance voltage source to test the different gases. Triggering is provided by a solid state opening switch voltage source that supplies ~150 kV, 10 ns risetime pulses at a rep rate up to 100 Hz in burst mode. A hermetically sealed spark gap with a Kel-F lining is used to house the switch and high pressure gas. This paper discusses in detail 50 k, 100 Hz switch operations with different gases. Gases tested include, dry Air, H2, N2, and SF6, as well as H2-N2, and N2-SF6 gas mixtures. Switch jitter as a result of triggering conditions is discussed, also including a comprehensive evaluation of jitter as a function of formative delay in the various gases.

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+ Analysis of Mesoband Single Element Pulsed Ring-Down Antennas for Implementation in Phased Array Systems
  Belt, D.; Mankowski, J.; Walter, J.; Dickens, J.; Kristiansen, M.; IEEE International Power Modulators and High Voltage Conference, Proceedings of the 2008 27-31 May 2008 Page(s):152 - 155 Digital Object Identifier 10.1109/IPMC.2008.4743602
Abstract:  In recent years, the pulsed ring-down antenna has become of great interest due to its compact size and high power on target potential. Since these systems are fairly new in study, it is often difficult to predict the overall performance without experimental evaluation. A pulsed ring-down antenna operates by charging the single element antenna with a high potential source and then closing a switch to develop transient wave reflections on the antenna, typical CW case analysis does not apply. For this reason, we have constructed a simulation model that allows us to predict the transient behavior of the structure. By utilizing the Comsol RF module transient analysis functions, we are able to characterize various parameters of different antennas, beginning with a dipole pulsed ring-down antenna operating around the 100 MHz range. After examining the simulated results against the experimental results for accuracy, we then moved to more complicated mesoband antenna structures. The simulation model developed within the COMSOL RF module allows us to examine various influential factors such as material losses, transient switching effects, structure capacitance, switch capacitance, and initial charging losses. With this, we are able to examine methods to improve the results in the far field such as capacitive spark gap loading and other capacitive storage methods. Utilizing the pulsed ring-down antenna model, we are able to give a better characterization of mesoband pulsed ring-down structures for implementation into a specific or multi-purpose phased array system.

[PDF]

+ Capacitor Evaluation For Compact HV Pulse Generation
  E. J. Matthews, A. A. Neuber, M. Kristiansen, Capacitor Evaluation For Compact HV Pulse Generation, to be published in the Proceedings of the 2008 IEEE International Power Modulator Conference Las Vegas, Nevada, USA, May 27-31, 2008.
Abstract:  The size of compact pulsed power generators capable of producing pulses with ~100 ns duration at Gigawatt power levels is primarily determined by the specific energy density of the utilized energy storage medium. Capacitors capable of delivering large pulsed currents at several 10 kV voltage levels have been most frequently used as the energy storage medium for portable pulse generators. To increase the specific energy density of the pulsed power generator, the capacitors are often voltage overstressed at the cost of capacitor life. However, rapid charging (milliseconds) of the capacitor immediately followed by discharging alleviates somewhat of the lifetime problem. For repetitive operation of the pulsed power generator, the charging/discharging energy loss is the more important parameter. The energy, WC, needed to charge a capacitor to a set voltage is measured along with the energy released, WR, by the capacitor under conditions corresponding to a compact Marx generator operating with ~10 Hz rep-rate into a ~20 Ohm load. For the tested capacitors with Mica as dielectric, the capacitor efficiency, eta, i.e. the ratio between WR and WC, is roughly equal to 97% and largely independent of the charging time. Also tested ceramic capacitors revealed an efficiency of ~90% for fast charging and an efficiency of ~94% for slower charging (from ~2 to 35 mus time constant).

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+ Compact High Power Microwave Generation
  Neuber, A. Young, M. Elsayed, J. Dickens, M. Giesselmann, M. Kristiansen, L. Altgilbers, Compact High Power Microwave Generation, Proceedings of the 2008 Army Science Conference, Orlando Florida, December 1-4, 2008. Presenter, P3E team contribution, paper was invited by L. Altgilbers.
Abstract:  Not Available
+ Comparison of HFCG and Compact Marx for Driving a High Power Microwave Load
  A. Neuber, A. Young, M. Elsayed, J. Walter, J. Dickens, M. Giesselmann, M. Kristiansen,and L.L. Altgilbers, Comparison of HFCG and Compact Marx for Driving a High Power Microwave Load, 12th IEE Conference on Megagauss Magnetic Field Generation, (Novosibirsk, Russia), July 2008, to be published.
Abstract:  Not Available
+ High-Current Compact FCG Seed Source Implementing Solid State Switching
  M. Elsayed, T. Holt, A. Young, A. Neuber, J. Dickens, M. Kristiansen, L.L. Altgilbers, and A.H. Stults, High-Current Compact FCG Seed Source Implementing Solid State Switching, to be published in the Proceedings of the 2008 IEEE International Power Modulator Conference Las Vegas, Nevada, USA, May 27-31, 2008.
Abstract:  Flux Compression Generators (FCGs) are some of the most attractive sources of single-use compact pulsed power available today due to their high energy density output and mobility. Driving FCGs requires some seed energy, which is typically provided by applying a high seed current, usually in the kilo-Ampere range for mid-sized helical FCGs. This initial current is supplied by a high-current seed source that is capable of driving an inductive load. High-current seed sources have typically been comprised of discharging large capacitors using spark-gaps and over-voltage triggering mechanisms to provide the prime power for FCGs. This paper will discuss a recent design of a self-contained (battery powered with full charge time less than 35 sec), single-use Compact Seed Source (CSS) using solid state components for the switching scheme developed at the Center for Pulsed Power and Power Electronics at Texas Tech University. The CSS developed is a system (0.007-m3 volume and weighing 13 lbs) capable of delivering over 250-J (~10 kA) into a 6-muH load with a trigger energy of micro-Joules at the TTL triggering level. The newly designed solid-state switching scheme of the CSS incorporates off-the-shelf high-voltage semiconductor components that minimize system cost and size as necessary for a single-use application. An in-depth and detailed evaluation of the CSS is presented primarily focusing on the switching mechanics and experimental characterization of the solid state components used in the system.

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+ Scaling and Improvement of Compact Explosively-Driven Ferroelectric Generators,
  D. Bolyard, A. Neuber, J. Krile, J. Walter, J. Dickens, and M. Kristiansen, Scaling and Improvement of Compact Explosively-Driven Ferroelectric Generators, to be published in the Proceedings of the 2008 IEEE International Power Modulator Conference Las Vegas, Nevada, USA, May 27-31, 2008.
Abstract:  Explosively-driven ferroelectric generators are capable of producing single-shot voltage pulses of more than 100 kV, while requiring no seed electrical source, being very compact, and shelf stable. Problems with ferroelectric generators are the low energy output, high dielectric constant of the ferroelectric material, low surface flashover voltage, inconsistent ferroelectric material quality, and uneven or excessive shockwave compression. Initial generator voltage waveforms show that breakdown occurred towards the end of the generator operation time. Several designs and methods have been tested and implemented to prevent surface flashover with varying results. The ferroelectric discs used for the generators were 0.4 inch thick, 1 inch diameter EC-64 PZT ceramic discs. Several six-disc generators were built and tested with resulting open-circuit voltage pulses of 80-140 kV with a FWHM of 2-4 mus. Further improvements to the generators have been designed to prevent surface flashover, improve the explosive driver element and propagating shockwave, as well as increasing the number of discs per generator. Measured output waveforms into varying loads including direct driven antennas will be shown and discussed.

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+ Shock Wave Simulation of Ferrite-Filled Coaxial Nonlinear Transmission Lines
  Sullivan, W.; Dickens, J.; Kristiansen, M.; Shock Wave Simulation of Ferrite-Filled Coaxial Nonlinear Transmission Lines; IEEE International Power Modulators and High Voltage Conference, Proceedings of the 2008 27-31 May 2008 Page(s):517 - 520 Digital Object Identifier 10.1109/IPMC.2008.4743706
Abstract:  Ferrite-filled coaxial shock lines have recently been used to significantly decrease the rise time of a high voltage pulse. This decrease can be enhanced by initially axially biasing the ferrite material with an applied external magnetic field, allowing for a faster transition from the unsaturated to the saturated state. The simulation of the ferrite material's operation, including saturation, is discussed as well as the simulation of coaxial nonlinear transmission lines. The project explores the rise time changes with variations of magnetic bias, ferrite geometry, input signal characteristics, and transmission line characteristics. Simulated waveforms are discussed for a nickel-zinc ferrite-filled coaxial line. The pulse steepening effect observed in electromagnetic shock lines occurs primarily because of an increase in phase velocity for points higher on the waveform due to the saturation of the ferrite material. An incident pulse of high enough amplitude will drive the ferrite material into saturation, decreasing the relative permeability to one. This saturation front propagates through the ferrite material in the direction of the incident wave until the entire material is saturated, producing a sub-nanosecond rise time pulse. The shock line is designed for a saturated impedance of 50 Ohms to couple easily into existing systems. Pulsed operation of up to low kilohertz repetition is desired and being explored. Applications of electromagnetic shock lines include laser triggering and ultra-wideband radar generation, as well as others.

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Publication Year:  2007
+ Electro-Explosive Fuse Optimization for Helical Flux Compression Generator Using a Non-Explosive Test Bed
  D. McCauley, D. Belt, J. Mankowski, J. Dickens, A. Neuber, M. Kristiansen, "Electro-Explosive Fuse Optimization for Helical Flux Compression Generator Using a Non-Explosive Test Bed," presented at the 2007 IEEE Pulsed Power and Plasma Science Conference, Albuquerque, NM June 17-22, 2007.
Abstract:  Helical Flux Compression Generators (HFCG) of 50 mm form factor have been shown to produce a maximum energy deposit of 3 kJ into a 3 muH inductor from a seed current. A large dl/dt into a coupled load is possible when an electro-explosive fuse is used. Previous work with a non-optimized fuse has produced ~100 kV into a 15Omega load which leads into a regime relevant for High Power Microwave (HPM) systems. It is expected that ~3()0kV can be achieved with the present 2 stage HFCG driving an inductive storage system with an electro-exploding fuse. In order to optimize the electro-explosive fuse design, a non-explosive test bed, which closely simulates the 45 kA HFCG output, is used. To optimize the tiise, effects of fuse material, fuse length, and fuse shape will be examined as well as the effects of various quenching materials. Our previous work has characterized fuse material but we are also looking into the effects of the processes used to create the fuse wire, such as tempered wire versus fully annealed wire. Additionally, to maximize the output voltage and minimize the fuse recovery time, we are optimizing the length of the fuse wire. For shorter fuse lengths, we are optimizing fuse shape as well as fuse length to find the best fuse recovery time. By optimizing the individual parameters of an electro-explosive fuse, the fuse as a whole will be optimized to produce maximum output voltage when used with an HFCG.

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+ Fuse and Load Testing with Mid-Sized, High Energy Density Flux Compression Generators,
  A. J. Young, T. A. Holt, M. A. Elsayed, A. A. Neuber, M. Kristiansen, L. L. Altgilbers, A. H. Stults, "Fuse and Load Testing with Mid-Sized, High Energy Density Flux Compression Generators," presented at the 2007 IEEE Pulsed Power and Plasma Science Conference, Albuquerque, NM June 17-22, 2007.
Abstract:  Not Available
+ Investigation of an FCG and Pulse Transformer Based Power Conditioning System
  T. A. Holt, A. J. Young, M. A. Elsayed, A. A. Neuber, M. Kristiansen, K. A. O'Connor, R. D. Curry, "Investigation of an FCG and Pulse Transformer Based Power Conditioning System," presented at the 2007 IEEE Pulsed Power and Plasma Science Conference, Albuquerque, NM June 17-22, 2007.
Abstract:  Not Available
+ Theoretical Pulsed Ring Down Antenna Array Performance
  Walter, J.; Dickens, J.; Mankowski, J.; Kristiansen, M.; Theoretical Pulsed Ring Down Antenna Array Performance Pulsed Power Plasma Science, 2007. PPPS 2007. Conference Record - Abstracts. IEEE 17-22 June 2007 Page(s):482 - 482
Abstract:  Summary form only given. High-power transient RF transmitters are currently being developed for multiple applications. One potential high- power pulsed source being considered is the pulsed ring- down source (PRDS). In a typical PRDS, electrical energy that is stored in the device structure is discharged through a switch, generating a damped ringing radiated waveform. The magnitude of the transmitted field is limited by parameters such as the overall device geometry and switch characteristics. The potential exists to increase the radiated far field power density by utilizing an array of PRDS transmitters. The performance of such an array depends on the triggering jitter of the device switches and the design of the individual radiating elements. The application of the array concept to pulsed ring-down sources using gas spark gap switches is examined. Theoretical array performance is discussed, taking into account practical switch jitter distributions, practical switch triggering schemes, and individual element characteristics.

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Publication Year:  2006
+ A Fabrication Method for a Mid-Sized, High Energy-Density, Flux Compression Generator
  T.A. Holt, A.J. Young, A.A. Neuber, M. Kristiansen, “A Fabrication Method for a Mid-Sized, High Energy-Density, Flux Compression Generator” presented at the 2006 International Conference on Megagauss Magnetic Field Generation and Related Topics, November 5-10, 2006 Santa Fe, New Mexico, USA
Abstract:  Not Available
+ A Fabrication Method for Helical Flux Compression Generators
  T.A. Holt, A.J. Young, A.A. Neuber, M. Kristiansen, “A Fabrication Method for Helical Flux Compression Generators,” presented at the 2006 Megagauss XI Conference, Sept. 10-14, 2006, Imperial College, London, UK
Abstract:  Not Available
+ A Flux Compression Generator Non-Explosive Test Bed for Explosive Opening Switches
  Belt, D.; Mankowski, J.; Neuber, A.; Dickens, J.; Kristiansen, M.; Conference Record of the 2006 Twenty-Seventh International Power Modulator Symposium, 2006. 14-18 May 2006 Page(s):456 - 459
Abstract:  Helical flux compression generators (HFCG) of a 50 mm form factor have been shown to produce output energies on the order of ten times the seeded value and a typical deposited energy of 3 kJ into a 3 muH inductor. Our previous work with a non-optimized fuse has produced-100 kV into a 15 load, which leads into a regime relevant for high power microwave (HPM) systems. It is expected that-300 kV can be achieved with the present 2-stage HFCG driving an inductive storage system with electro-exploding fuse. In order to optimize the electro-explosive wire fuse, we have constructed a non-explosive test bed which simulates the HFCG output with high accuracy. We have designed and implemented a capacitor based, magnetic switching scheme to generate the near exponential rise of the HFCG. The varying inductance approach utilizes 4 stages of inductance change and is based upon a piecewise linear regression model of the HFCG waveform. The non-explosive test bed will provide a more efficient method of component testing and has demonstrated positive initial fuse results

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+ Dielectric Surface Flashover Research at Texas Tech University
  A. Neuber, H. Krompholz, J. Dickens, M. Kristiansen, “Dielectric Surface Flashover Research at Texas Tech University,” presented at the 1st Euro-Asian Pulsed Power Conference, Sept. 18 -22, 2006, Chengdu, China.
Abstract:  Not Available
+ Electro-explosive fuse development for helical flux compression generators
  D. Belt, J. Dickens, J. Mankowski, A. Neuber, and M. Kristiansen, “Electro-explosive fuse development for helical flux compression generators,” presented at the 2006 International Conference on Megagauss Magnetic Field Generation and Related Topics, November 5-10, 2006 Santa Fe, New Mexico, USA
Abstract:  Not Available
+ Helical Flux Compression Generator Non- Explosive Test Bed for Electro-Explosive Fuses
  D. Belt, J. Dickens, J. Mankowski, A. Neuber, M. Kristiansen, “Helical Flux Compression Generator Non- Explosive Test Bed for Electro-Explosive Fuses”, presented at the 27th Power Modulator Symposium and 2006 High Voltage Workshop May 14-18, 2006, Washington, DC.
Abstract:  Not Available
+ Interface Breakdown During High Power Microwave Transmission
  A. Neuber, J. Krile, G. Edmiston, H. Krompholz, J. Dickens, M. Kristiansen ,“Interface Breakdown During High Power Microwave Transmission,” presented at the 13th EML Symposium, May 22-25, 2006, Berlin, Germany.
Abstract:  Not Available
+ The Impact of Water Conductivity, Electrode Material, and Electrode Surface Roughness on the Pulsed Breakdown Strength of Water
  Wetz, D.; Mankowski, J.; McCauley, D.; Dickens, J.; Kristiansen, M.; Conference Record of the 2006 Twenty-Seventh International Power Modulator Symposium, 2006. 14-18 May 2006 Page(s):104 - 107
Abstract:  Experimental results are presented on the impact water conductivity, electrode material, and electrode surface roughness have on the dielectric strength of water. A 2 mm water gap was tested under pulsed conditions with maximum electric fields in excess of 1.5 MV/cm. Bruce profiled electrodes manufactured from various materials including molybdenum, aluminum, copper, tungsten, nickel, stainless steel, and zinc oxide, which have work functions ranging from 4.2 eV to 5.3 eV, have been tested. The roughness average of the various surfaces was varied from 0.1 mum to 1.96 mum and the conductivity of the water within the gap was varied from 1muS/cm to 39 muS/cm to determine the impact each has when tested in combination with the various electrode materials and surface roughnesses. Conclusions are made as to the effect each of these factors has on the holdoff strength of a water dielectric system

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+ Virtual Cathode Oscillator Component Optimization
  Chen, Y.-J.; Mankowski, J.; Walter, J.; Kristiansen, M.; Conference Record of the 2006 Twenty-Seventh International Power Modulator Symposium, 2006. 14-18 May 2006 Page(s):157 - 160
Abstract:  Recent research efforts at TTU include a simple aluminum cathode for E-beam generation in a virtual cathode oscillator (vircator). As a continuation of these results, we are fabricating and testing several different types of cathodes for the vircator driven by a Marx generator and a pulse forming line (400 kV, 60 ns, 30 Omega). The cathodes, each with an emitting area of ~32 cm2, are made from aluminum and oxygen free copper fashioned to similar geometries with either a chemical etch or a CNC machine process. The vircator is tested with all of these cathodes and evaluated for beam voltage, current, and HPM generation. In addition to the cathode testing, several stainless steel and tungsten anode meshes with varying transparencies (50%-80%) are evaluated

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Publication Year:  2005
+ A Compact, Repetitive, 500kV, 500 J, Marx Generator
  Neuber, A.A.; Chen, Y.J.; Dickens, J.C.; Kristiansen, M.; 2005 IEEE Pulsed Power Conference; June 2005 Page(s):1203 - 1206
Abstract:  The electrical characteristics and design features of a low inductance, compact, 500 kV, 500 J, 10 Hz repetition rate, Marx generator are discussed. While benefiting from the large energy density of mica capacitors, 4 mica capacitors were utilized in parallel per stage, keeping the parasitic inductance per stage low. Including the spark-gap switches, a stage inductance of 55 nH was measured, which translates with 100 nF capacitance per stage to ~ 18.5 ¿ characteristic Marx impedance. Using solely inductors, ~ 1 mH each, as charging elements instead of resistors enabled charging the Marx within less than 100 ms with little charging losses. The pulse width of the Marx into a matched resistive load is about 200 ns with 50 ns rise-time. Repetitive HPM generation with the Marx directly driving a small Vircator has been verified. The Marx is fitted into a tube with 30 cm diameter and a total length of 0.7 m. We discuss the Marx operation at up to 21 kV charging voltage per stage, with repetition rates of up to 10 Hz in burst mode primarily into resistive loads. A lumped circuit description of the Marx is also given, closely matching the experimental results.

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+ An Ion Beam Sputtering System for Electrode Surface Conditioning
  Wetz, D.; Mankowski, J.; Kristiansen, M.; IEEE Conference Record - Abstracts. IEEE International Conference on Plasma Science, 2005. ICOPS '05. 20-23 June 2005 Page(s):123 - 123
Abstract:  Summary form only given. In the past there has been considerable research performed using electromagnetic plasma thrusters as the primary ion source in sputtering applications. In the experiments conducted here, thin film coatings of various hard metallic alloys and oxides were applied to stainless steel electrodes using ion beam deposition. An SPT type Hall effect thruster capable of producing an ion beam with energies between 150 eV and 350 eV was used as the deposition ion source. The surface coatings were applied to Bruce profiled stainless steel electrodes which have an effective surface area of 5 cm2 and a roughness average of roughly 70 nm. The electrodes were then examined using an optical profiler to accurately measure the roughness average of the thin film coating as well as the effective layer thickness. A comparison of the results obtained from each surface material is performed

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+ Characaterization of Transient Antennas
  "Characaterization of Transient Antennas", proceeding of the 15th Int’l. Pulsed Power Conference, Monterey, CA, June 13-17, 2005 (with J. Walter and J. Dickens).
Abstract:  Not Available
+ Compact Pulsed Power at TTU
  A. Neuber, M. Kristiansen, J. Dickens, M. Giesselmann, “Compact Pulsed Power at TTU,” 3rd Annual Multi-Functional Warhead Workshop, 30 November – 1 December 2005, Redstone Arsenal, Huntsville, AL.
Abstract:  Not Available
+ Multi-Frequency and Multi-Mode Microwave Identification in a Vircator Research
  Xupeng Chen; Dickens, J.C.; Hatfield, L.L.; Mankowski, J.; Kristiansen, M.; 2005 IEEE Pulsed Power Conference, June 2005 Page(s):190 - 193
Abstract:  In virtual cathode oscillator (VIRCATOR) research, multi-frequency and multi-mode microwaves are coupled out and propagate along a waveguide. Identifying the microwave propagating modes has become a priority work for further research on microwave radiation physical mechanisms. Generally, an antenna matrix at the end of an open waveguide, which can shape the radiated microwave power distribution, is used to identify the microwave propagating modes [1-2]. Actual microwave radiation mechanisms in a VIRCATOR are complicated. Multi propagating modes and multifrequency microwaves coexist simultaneously, which challenges the antenna matrix method. In this paper, based on microwave propagating theory in a waveguide, a new method is proposed to identify multi-frequency and multi-mode microwaves, which is partially justified by the experimental data at Texas Tech University.

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+ The Impact of Electrode Area and Surface Roughness on the Pulsed Breakdown Strength Water
  Wetz, D.; Mankowski, J.; Kristiansen, M.; 2005 IEEE Pulsed Power Conference, June 2005 Page(s):1163 - 1166
Abstract:  Experimental results are presented on the degree to which electrode surface area and surface roughness impacts the dielectric strength of water. A 2 mm water gap was tested under pulsed conditions with maximum electric fields in excess of 1 MV/cm and maximum currents of more than 5 kA. Six different pairs of stainless steel electrodes, each having a unique Bruce profile and thus a different effective surface area, were used to achieve a uniform electric field across the gap. The differing electrode pair profiles, with effective areas ranging from 0.5 cm2 to 76 cm2, were designed to minimize the change in gap capacitance. Prior to each test, a different roughness average, ranging from 0.26 ¿m to 1.96 ¿m, was applied to the electrodes. Conclusions are made as to the effect both electrode surface area and surface roughness has on the holdoff voltage of water dielectric systems. In addition, shadowgraph images of pre-breakdown events are presented.

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+ The Impact of Electrode Material on the Pulsed Breakdown Strength of Water
  Wetz, D.; Mankowski, J.; Dickens, J.; Kristiansen, M.; 2005 IEEE Pulsed Power Conference, June 2005 Page(s):935 - 938
Abstract:  In the experiments presented here, various electrode materials were tested in an effort to determine the impact each has on increasing the dielectric strength of water. Prior investigations have tested materials such as stainless steel, copper, nickel, gold, silver, and cuprous oxide [1-4]. In our experiments, thin film coatings of various metallic alloys and oxides were applied to Bruce profiled stainless steel electrodes with an effective area of 5 cm2. An ion beam sputtering process was used to apply the coatings with thicknesses of several hundred nm. The electrodes were then tested across a water gap, with pulse lengths in both the microsecond and nanosecond time regimes. Electric fields in excess of 8 MV/cm were applied. Conclusions are made as to the impact electrode material has on the pulsed breakdown strength of water.

[PDF]

Publication Year:  2004
+ Compact FCG Driven Inductive Energy Storage System
  J.-C. Hernandez, A. A. Neuber, M. Giesselmann, J. C. Dickens, and Magne Kristiansen, ”Compact FCG Driven Inductive Energy Storage System,” in Proceedings of MegaGauss X, Berlin, Germany, July 18 -23, p. 144-147, 2004,.
Abstract:  Not Available
+ Compact Pulsed Power
  M. Kristiansen, A. Neuber, J. Dickens, M. Giesselmann, and S. Shkuratov, “Compact Pulsed Power,“ MegaGauss X, Berlin, Germany, July 18 -23, p. 169-175, 2004. (Invited)
Abstract:  Not Available
+ Compact Pulsed Power
  "Compact Pulsed Power", 5th International Sy mposium on Pulsed Power and Plasma Applications, Chang Won, Gyeong-Nam, Korea. October 18-21, 2004.
Abstract:  Not Available
+ Compact Pulsed Power
  M. Kristiansen, J. Dickens, H. Krompholz, M. Giesselmann, A. Neuber, J. Mankowski, L. Hatfield, “Compact Pulsed Power,“ Proceedings of the 5th International Symposium on Pulsed Power and Plasma Applications, Oct. 18-20, Chan-Won, Korea, p. 10-15, 2004. (Invited paper)
Abstract:  Not Available
+ Impact of surface conditioning of large area electrodes on the dielectric strength of water
  Wetz, D.; Mankowski, J.; Truman, K.; Kristiansen, M.; Conference Record of the Twenty-Sixth International Power Modulator Symposium, 2004 and 2004 High-Voltage Workshop. 23-26 May 2004 Page(s):512 - 515
Abstract:  Experimental results are presented on the impact electrode material and surface treatment has on the dielectric strength of water. A 4 mm water gap was tested under pulsed conditions with pulse widths greater than 1 /spl mu/s, peak electric fields over 2 MV/cm and peak currents over 15 kA. 304 stainless steel electrodes machined with a Bruce profile and an effective area of 5 cm/sup 2/ were tested with surface roughnesses ranging from .34 /spl mu/m to 1.41 /spl mu/m. Results comparing electrodes that have additionally been electropolished are compared to those without an additional treatment. These various surface treatments remove microprotrusions from the electrode's surface which reduce field enhancements across the electrode surface. It is believed that this technique will minimize the number of breakdown initiation points thereby increasing the dielectric strength. Results are given on the degree to which each finish improves the dielectric strength of water.

[PDF]

+ Modeling of Pulsed Radiating Structures
  "Modeling of Pulsed Radiating Structures", 2nd European Pulsed Power Symposium 2004, Hamburg, Germany, September 20-23, 2004 (with John Walter and J. Dickens).
Abstract:  Not Available
+ The effect of area on pulsed breakdown in water
  Truman, K.; Mankowski, J.; Wetz, D.; Kristiansen, M.; Conference Record of the Twenty-Sixth International Power Modulator Symposium, 2004 and 2004 High-Voltage Workshop. 23-26 May 2004 Page(s):126 - 128
Abstract:  Experimental results are presented on the degree to which electrode surface area impacts the dielectric strength of water. A water gap of 4 mm was tested under pulsed conditions with a maximum electric field in excess of 1 MV/cm and a maximum current of more than 20 kA. Stainless steel electrodes with a Bruce profile were used to generate a uniform electric field across the water gap. The profile of the electrodes enabled effective areas ranging from 0.5 cm/sup 2/ to 75 cm/sup 2/ while minimizing the change in capacitance of the water gap. Conclusions are made as to the effect electrode surface area has on the holdoff voltage and holdoff time of water dielectric systems.

[PDF]

Publication Year:  2003
+ Cavity resonance effect on a coaxial vircator
  Xupeng Chen; Dickens, J.; Eun Ha Choi; Mankowski, J.; Hatfield, L.L.; Kristiansen, M.; Digest of Technical Papers. PPC-2003. 14th IEEE International Pulsed Power Conference, 2003. Volume 2, 15-18 June 2003 Page(s):1165 - 1168 Vol.2
Abstract:  Traditionally, the radiated microwave frequency in a coaxial vircator is considered to be determined primarily by the virtual cathode oscillation frequency and the electron reflection frequency. However, some experiments at TTU show that the interaction between the virtual cathode oscillation and the cavity is a key in determining the microwave frequency and propagating mode. Particularly, we observe that the E-beam plays an important role in the cavity formation. Some possible explanations, including a virtual cavity concept, are proposed. The cavity resonance effect on a coaxial virtual cathode oscillator has been investigated in detail. The understanding of the E-beam characteristics is critical in optimizing the design of the cylindrical diode to avoid the microwave frequency shifting and mode competition.

[PDF]

+ Conductivity measurements of explosively shocked aluminum and OFHC copper used for armature material in a magnetic flux compression generator
  Hemmert, D.; Mankowski, J.; Rasty, J.; Neuber, A.; Dickens, J.; Kristiansen, M.; Digest of Technical Papers, PPC-2003. 14th IEEE International Pulsed Power Conference, 2003. Volume 2, 15-18 June 2003 Page(s):1073 - 1076 Vol.2
Abstract:  Modeling and characterization of a magnetic flux compression generator (MFCG) requires detailed knowledge of the changes in conductivity of the MFCG materials during the shock-loading phase. In the studies reported here, a thin metallic strip is shocked with an explosively generated shock wave produced from a charge of composition C-4. The shock wave is intended to simulate the shock wave and pressures produced in MFCG research currently being conducted at Texas Tech University. These pressures are estimated to be between 1 and 3 GPa. The experimental setup is arranged so that the shapes of the metallic strip and shock front are the same, as confirmed using optical fibers. This was to ensure that the test sample was shocked uniformly. The metallic test strip is pulsed with a 70 A current pulse during application of the shock wave. The current and voltage across the test sample are measured directly to determine the change in conductivity. Pressure measurements are conducted in separate tests under similar conditions using strain gauges. The results are then compared to results determined previously using a split Hopkinson pressure bar apparatus (SHPB).

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+ Design criteria for prevention of armature "turn-skipping" in helical magnetic flux compression generators
  Rasty, J.; Le, X.; Dickens, J.; Neuber, A.; Kristiansen, M.; Pulsed Power Conference, 2003. Digest of Technical Papers. PPC-2003. 14th IEEE International Volume 2, 15-18 June 2003 Page(s):1077 - 1080 Vol.2
Abstract:  Helical magnetic flux compression generators (MFCGs) are capable of producing ultra-high power electric pulses by trapping and compressing a seed magnetic field into a load coil via an explosive-driven armature. The efficiency of helical MFCGs is generally very low, about 10%, due to large magnetic flux losses. One of the main sources of magnetic flux loss is the "turn-skipping" phenomenon, in which the expanding armature fails to establish contact with every turn of the helical coil, resulting in magnetic flux loss in the skipped turns of the coil. The "turn-skipping" phenomenon is related to non-uniform or asymmetric expansion of the armature, as well as detonation end effects. Equations describing the "turn skipping" phenomenon are developed in terms of the eccentricity of the armature with respect to the helical coil, the armature's wall thickness variations and the length of the detonation end effect. Design criteria for prevention of "turn-skipping" are presented in order to achieve optimum MFCG performance.

[PDF]

+ Experimental results of a 2 GW vircator
  Mankowski, J.J.; Choi, E.H.; Dickens, J.C.; Xupeng Chen; Kristiansen, M.; IEEE Conference Record - Abstracts. The 30th International Conference on Plasma Science, 2003. ICOPS 2003. 2-5 June 2003 Page(s):187
Abstract:  Summary form only given. Experimental findings on the coaxial virtual cathode oscillator (vircator) at Texas Tech University are reported. Recent modifications to the system include extending the pulse forming line that now provides an applied diode voltage of 600 kV for 70 nanoseconds at 60 kA. Other modifications include diode voltage, current, and radiated field diagnostics. In this initial phase of experiments, copper reflectors were installed within the diode to provide a simple means of microwave feedback to assist in the e-beam modulation. Thus far we have observed microwave peak power output with feedback reflectors as high as 2 GW corresponding to an efficiency of -6%. The mode observed at these high efficiencies is almost entirely TE/sub 11/. At lower efficiencies, both TM/sub 01/, and TE/sub 11/ modes are observed. These results suggest mode competition at lower efficiencies.

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+ Ferromagnetic and ferroelectric materials as seed sources for magnetic flux compressors
  Schoeneberg, N.; Walter, J.; Neuber, A.; Dickens, J.; Kristiansen, M.; Digest of Technical Papers. PPC-2003. 14th IEEE International Pulsed Power Conference, 2003. Volume 2, 15-18 June 2003 Page(s):1069 - 1072 Vol.2
Abstract:  permanent magnet based systems. Permanent magnets provide a larger energy-to-volume ratio given that the use of capacitors requires a power source as well as charging and firing circuitry. A recent design developed at Texas Tech University's Center for Pulsed Power and Power Electronics [S.I. Shkuratov, et al., 2002], focused on the demagnetization of a Neodymium-Iron-Boron magnet (Nd/sub 2/Fe/sub 14/B, B/sub r/= 1.23 T) by a shockwave generated from high explosives. The maximum specific energy achieved with this design was only 2.3 J/kg, which may not be sufficient for effectively seeding an FCG (fast capacitors have at least 20 J/kg). The same magnets were used with an alternative design, referred to as a strip FCG, which utilizes opposing magnets to generate initial magnetic field intensity within an air gap. The air gap exists between a central tube, filled with high explosives, and metal strips placed between the magnets a few millimeters off-axis. The detonation of the explosive causes the expansion of the central tube, subsequently compressing the flux into the strips and then into the load. The original strip FCG design [B.A. Bojko, et al., 1994] used oxide-barium magnets (B/sub r/= 0.2T), which produced an estimated specific energy of 5.27 J/kg into a low inductance load. These magnets were replaced with the Nd/sub 2/Fe/sub 14/B (B/sub r/= 1.23 T) magnets in order to achieve better performance, which will be analyzed with respect to the specific energy. In addition, a design utilizing a shocked ferroelectric material, PZT, as a seed current source is discussed. An explosively generated shock wave is passed through a ferroelectric material, generating a current that establishes the initial seed flux for an FCG. Preliminary tests of the ferroelectric sources indicate a possible theoretical specific energy of more than 11 J/kg or 25 J/dm/sup 3/. A comparison of the designs will be discussed with regard to the specific energy produced and the effectiveness of each to seed FCG's.

[PDF]

+ Reflex-triode geometry of the virtual-cathode oscillator
  Lara, M.B.; Mankowski, J.; Dickens, J.; Kristiansen, M.; Digest of Technical Papers. PPC-2003. 14th IEEE International Pulsed Power Conference, 2003. Volume 2, 15-18 June 2003 Page(s):1161 - 1164 Vol.2
Abstract:  An eight-stage four-hundred kilovolt Marx bank, in connection with a 60 nanosecond pulse-forming line, is constructed and utilized as a pulsed source to power a planar version of the virtual cathode oscillator (vircator). Eight .1/spl mu/F capacitors, charged to 50 kV each, are switched in series by dry-air pressurized spark gaps. The energy from the bank charges a 23 ohm oil transmission line, breaking a peaking gap when the maximum voltage is reached, delivering a 60 ns-300 kV pulse to the diode. The design of the planar or reflex-triode geometry vircator is based upon claims of high efficiency by Didenko et al. A previously constructed TTU vircator includes a unique E-beam source, the brush cathode; in which a circular array of pins is used as an explosive field emission source to produce relatively high beam currents. The anode consists of a round wire mesh through which the E-beam passes, generating a dense cloud of negative charge known as a virtual cathode. This initial phase of testing is composed of basic operation of the entire system and baseline output power and efficiency measurements.

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+ Single-Shot and Overstressing of High Voltage Capacitors for Compact Arkadiev-Marx Genertor
  "Single-Shot and Overstressing of High Voltage Capacitors for Compact Arkadiev-Marx Genertor", Proc.14th IEEE International Pulsed Power Conference, Dallas, TX, June 16-19, 2003 p. 723 (with S. Shkuratov, E. Talantsev, and J. Dickens).
Abstract:  Not Available
+ Small sized MFCG for driving a high impedance load
  Hernandez, J.-C.; Neuber, A.A.; Dickens, J.C.; Kristiansen, M.; Digest of Technical Papers. PPC-2003. 14th IEEE International Pulsed Power Conference, 2003. Volume 2, 15-18 June 2003 Page(s):1065 - 1068 Vol.2
Abstract:  End-initiated small volume magnetic flux compression generators (MFCG) have at least one order of magnitude higher energy density (by weight or volume) than capacitive energy storage with similar discharge time characteristics. Since the prime energy is built into the MFCG in form of HE, the capacitor looses even more ground if the necessary prime energy source and the charging supply are included in the weight/volume balance. However, simple MFCGs with a single helix produce high output energy only into low inductance loads, thus producing several 100 kA of current at a voltage level of only a few 10 kV. Many pulsed power devices require less current but a considerably higher voltage level. Two approaches for achieving a higher output voltage level, both utilizing two staged MFCGs, have been reported in the open literature. The first employs a more traditional transformer coupling; the second relies on a dynamic transformer or flux-trapping scheme. Although the traditional transformer coupling has theoretically the better efficiency, we chose the latter approach for our generator design, mostly since it requires a smaller number of components. Our generator has a total length of 250 mm, a helix inner diameter of 51 mm, and is wound with Teflon insulated stranded wire of different sizes in the range from AWG 12 to AWG 22. We have presently achieved an energy gain of /spl sim/ 8 and will discuss the generator performance based on experimental current/voltage waveforms.

[PDF]

+ Space Charge Limited Current for a 1-D Cylindrical Diode
  "Space Charge Limited Current for a 1-D Cylindrical Diode", Proc. 14th IEEE International Pulsed Power Conference, Dallas, TX, June 16-19, 2003 p. 467 (with X. Chen, J. Dickens, E. Choi).
Abstract:  Not Available
Publication Year:  2002
+ All-Explosive Pulsed Power Generator System
  A. Neuber, S. Shkuratov, E. Talantsev, J. Walter, T. Holt, J. Dickens, and M. Kristiansen, “All-Explosive Pulsed Power Generator System,” at the Ninth International Conference on Megagauss Magnetic Field Generation and Related Topics, Moscow – St. Petersburg, July 7-14, 2002.
Abstract:  Not Available
+ Dependence of Flux Losses on MCG Helix Geometry
  A. Neuber, T. Holt, J. Hernandez, J. Dickens, and M. Kristiansen, “Dependence of Flux Losses on MCG Helix Geometry,” presented at the 14th International Conference on High-Power Particle Beams, Albuquerque, NM, June 23 - 28, 2002.
Abstract:  Not Available
+ Explosive-Driven Generation of Transient Antennas
  A. Neuber, N. Schoeneberg, J. Dickens, and M. Kristiansen, “Explosive-Driven Generation of Transient Antennas,” presented at the Ninth International Conference on Megagauss Magnetic Field Generation and Related Topics, Moscow – St. Petersburg, July 7-14, 2002.
Abstract:  Not Available
+ Feasibility study of an explosively formed transient antenna
  Neuber, A.; Schoeneberg, N.; Dickens, J.; Kristiansen, M.; Conference Record of the Twenty-Fifth International Power Modulator Symposium, 2002 and 2002 High-Voltage Workshop. 30 June-3 July 2002 Page(s):374 - 377
Abstract:  The feasibility of utilizing the chemical energy stored in high explosives to generate an antenna capable of radiating for several microseconds is studied. Crucial parameters such as conductivity as a function of time, maximum achievable antenna length for given initial device volume and weight, and material dependence are assessed by sub microsecond optical and electrical diagnostics. By utilizing a rotating framing mirror camera with up to 4 Megaframes per second, which produces a color image sequence consisting of 125 frames, possible premature breakup of the transient antenna rod is measured with adequate spatial and temporal resolution, thus revealing a rod growth velocity of a few millimeters/microsecond. Electrical diagnostic, primarily aimed at the conductivity between selected points along the rod propagation, enables to make a connection with the observed behavior based on the optical diagnostics. Maintaining electrical contact at the base of the device while the rod is fully formed is crucial and will be discussed in detail.

[PDF]

+ Geometry Impact on Flux Losses in MFCGs
  A. Neuber, T. Holt, J. Hernandez, J. Dickens, and M. Kristiansen, “Geometry Impact on Flux Losses in MFCGs,” presented at the Ninth International Conference on Megagauss Magnetic Field Generation and Related Topics, Moscow – St. Petersburg, July 7-14, 2002.
Abstract:  Not Available
+ Nanosecond pulsed breakdown for point-plane geometries at moderate voltage
  Nanosecond pulsed breakdown for point-plane geometries at moderate voltage”, H. Krompholz, L. Hatfield, M. Haustein, J. Spears, M. Kristiansen, AMEREM 2002, Annapolis, Md, June 2002
Abstract:  Not Available
Publication Year:  2001
+ Advanced Modeling of an Exploding Flux Compression Generator using Lumped Element Models of Magnetic Diffusion
  M. Giesselmann, T. Heeren, A. Neuber and M. Kristiansen, “Advanced Modeling of an Exploding Flux Compression Generator using Lumped Element Models of Magnetic Diffusion”, Proceedings of the 2001 Conference on Pulsed Power and Plasma Science, Las Vegas, Nevada, June 17-22, 2001, p. 162...165.
Abstract:  Not Available
+ Calculating stator losses in a helical MFCG
  Benton, T.; Kuo-Ta Hsieh; Stefani, F.; Neuber, A.; Kristiansen, M.; Pulsed Power Plasma Science, 2001. PPPS-2001. Digest of Technical Papers Volume 1, 17-22 June 2001 Page(s):85 - 89 vol.1
Abstract:  This paper analyzes the transient electromagnetic, thermal, and structural behavior of the stator turns in a simple helical magnetic flux compression generator (MFCG). The main objective is to quantify the losses due to Ohmic heating and flux trapping in the conductors, including the effect of armature motion and armature proximity on the current distribution. The electric current excitation used in the modeling is based on experimental data from tests on a research MFCG. The electromagnetic (EM) and thermal analyses were conducted using EMAP3D, a 3D finite element analysis (FEA) code developed at The University of Texas at Austin (UT), which has the capability to model relative motion and sliding between conductors. Structural analyses were conducted using a version of DYNA3D that allows state data from EMAP3D to be used as input. Details of the analyses include temperature dependence on electrical, thermal, and mechanical properties.

[PDF]

+ Calculation of air temperature and pressure history during the operation of a flux compression generator
  Xiaobin Le; Rasty, J.; Neuber, A.; Dickens, J.; Kristiansen, M.; Pulsed Power Plasma Science, 2001. PPPS-2001. Digest of Technical Papers Volume 2, 17-22 June 2001 Page(s):939 - 942 vol.2
Abstract:  During the operation of magnetic flux compression generators (MFCG), the gas-plasma, shocked by the rapidly expanding armature, could lead to electrical arcing across the gas between the armature and the stator at locations where physical contact between the armature and stator has not yet occurred. This will result in a loss of magnetic flux and a decrease in the electrical efficiency of the MFCG. Therefore, knowledge of the ensuing gas temperature and pressure histories is necessary for identification of loss mechanisms in an effort to optimize the efficiency of MFCGs. This paper describes the procedure for estimating the air temperature and pressure histories via finite element (FE) simulation of the armature expansion and its ensuing contact with the stator in an MFCG. First, the validity of the FE model was verified by comparing deformation contours obtained from the simulations to those obtained experimentally via high-speed photography. Utilizing the pressure history data obtained from the FE results, the air temperature was theoretically calculated. The results indicate that the air pressure and temperature in an MFCG, having a compression ratio of 1.8, could be as high as 30 MPa and 4000/spl deg/ Kelvin, respectively.

[PDF]

+ Compact explosive driven shock wave ferromagnetic generators
  Shkuratov, S.I.; Talantsev, E.F.; Kristiansen, M.; Dickens, J.; Hernandez, J.C.; Neuber, A.; Digest of Technical Papers, Pulsed Power Plasma Science, 2001. PPPS-2001. Volume 1, 17-22 June 2001 Page(s):158 - 161 vol.1
Abstract:  The results are presented of tests with compact, explosively driven shock wave ferromagnetic generators. The shock wave from a high explosive charge is passed along the axis of a cylindrical, hard magnet. Two types of permanent magnets were used in the experiments: rare-earth NdFeB cylinders (D = 2.5 cm, L = 1.9 cm) and hard ferrite BaFe/sub 2/O/sub 3/ cylinders (D = 2.2 cm, L = 2.5 cm). The shock wave demagnetizes the cylinder, reducing the flux from the remnant value to zero. This change in flux generates a voltage in the winding. The current generated in the loads of the generators yielded a peak of 0.75 kA. The operation of the shock wave ferromagnetic generators was analyzed by the Maxwell 3D code. An analysis is given on the specific features of pulse generation in a system like this.

[PDF]

+ Conductivity measurements of MFCG armature material under shock and high strain rates utilizing a split-hopkinson pressure bar apparatus
  Hemmert, D.; Rasty, J.; Neuber, A.; Dickens, J.; Le, X.; Kristiansen, M.; Digest of Technical Papers, 2001 Pulsed Power Plasma Science, PPPS-2001. Volume 1, 17-22 June 2001 Page(s):265 - 268
Abstract:  Not Available
+ Effect of Electron-Beam Pulse Length on Microwave Efficiency of Coaxial Vircator
  "Effect of Electron-Beam Pulse Length on Microwave Efficiency of Coaxial Vircator", Proc. 13th IEEE International Pulsed Power Conference and the 28th IEEE Conference on Plasma Science, Las Vegas, NV, June 17-22, 2001 (with W. Jiang, K. Woolverton, and J. Dickens).
Abstract:  Not Available
+ Experimental and numerical investigation of armature/stator contact in magnetic flux compression generators
  Rasty, J.; Xiaobin Le; Neuber, A.; Dickens, J.; Kristiansen, M.; Digest of Technical Papers, Pulsed Power Plasma Science, 2001. PPPS-2001. Volume 1, 17-22 June 2001 Page(s):106 - 109 vol.1
Abstract:  The efficiency of a magnetic flux compression generators (MFCG) is highly dependent on the expanding characteristics of the exploding armature and the nature of contact between the armature and the surrounding stator coil. A hydrodynamic finite element (FE) model was developed to simulate the expansion characteristics of the armature and its ensuing impact with the stator. The effectiveness of the FE model to simulate the explosive behavior of the armature was qualified by comparing the numerical results with experimentally measured parameters. Specifically, the radial displacement of the armature as well as the axial velocity of the armature/stator contact point were measured experimentally and compared with numerical results showing excellent agreement between the two. The results indicated that the radial and axial velocity with which the armature impacted the stator did not change through the length of the armature. However, the results showed that the velocity with which the contact point between the armature and the stator traveled along the length of the armature decreased as the explosion process went on. As expected, the axial propagation velocity of the contact point was found to be at its highest value (2.25 X detonation velocity) at the region close to the detonation end while approaching the detonation velocity at points away from the detonation end.

[PDF]

+ Experimental study of compact explosive driven shock wave ferroelectric generators
  Shkuratov, S.I.; Kristiansen, M.; Dickens, J.; Neuber, A.; Altgilbers, L.L.; Tracy, P.T.; Tkach, Y.; Digest of Technical Papers, Pulsed Power Plasma Science, 2001. PPPS-2001. Volume 2, 17-22 June 2001 Page(s):959 - 962 vol.2
Abstract:  The design of explosive driven ferroelectric generators is presented and experimental data are discussed. The active elements are lead zirconium titanate (PZT) disks with diameter D=25 mm and thicknesses H=2.5 mm and H=6 mm and PZT cylinders with D=21 mm and H=25 mm. The high explosive charge was varied from 4.2 g to 30 g. Two different ways to initiate shock waves in the active elements were used: explosively driven flyer plates and direct action of high explosives. The data presented is for the maximum power into a resistive load.

[PDF]

+ Experimental study of compact explosive-driven shock wave ferroelectric generators
  Shkuratov, S.; Kristiansen, M.; Dickens, J.; Neuber, A.; Altgilbers, L.L.; Tracy, P.T.; Tkach, Y.; IEEE Conference Record - Abstracts. Pulsed Power Plasma Science, 2001.17-22 June 2001 Page(s):227
Abstract:  Summary form only given. The design of shock wave ferroelectric generators driven by high explosives is presented and experimental data are discussed. The active elements are lead zirconium titanate (PZT) disks with diameter D=25 mm and thickness L=2.5 mm, and PZT cylinders with D=21 mm and L=25 mm. The high explosive charge was varied from 4.2 g to 30 g. Two different ways to initiate shock waves in the active elements were used: explosively driven flyer plates and direct action of high explosives. The data are presented on the maximum power released in the resistive load and on the effect of the load inductance and the load capacitance on the amplitude of the pulse produced. The experimental results are discussed in comparison to numerical simulation with the commercial circuit simulator PSPICE. An analysis is given of the specific features of pulse generation in a system like this

[PDF]

+ Explosive Pulsed Electric Power Generation
  "Explosive Pulsed Electric Power Generation". Proc. 13th IEEE International Pulsed Power Conference and the 28th IEEE Conference on Plasma Science, Las Vegas, NV, June 17-22, 2001 (with J. Gregor).
Abstract:  Not Available
+ Explosive-Driven Moving Magnet Generators
  "Explosive-Driven Moving Magnet Generators", Proceedings of 13th IEEE International Pulsed Power Conference, Las Vegas, Nevada, June 2001, p. 227 (with S.I. Shkuratov, M. Kristiansen, and J.C. Dickens).
Abstract:  Not Available
+ Gas breakdown in the sub-nanosecond regime with voltages below 15 kV
  Krompholz, H.; Hatfield, L.L.; Kristiansen, M.; Hemmert, D.; Short, B.; Mankowski, J.; Brown, M.; Altgilbers, L.; Digest of Technical Papers, Pulsed Power Plasma Science, 2001. PPPS-2001. Volume 1, 17-22 June 2001 Page(s):487 - 490 vol.1
Abstract:  Gaseous breakdown in the sub-nanosecond regime is of interest for fast pulsed power switching, short pulse electromagnetics and for plasma limiters to protect devices from high power microwave radiation. Previous investigations of sub-nanosecond breakdown were mainly limited to high-pressure gases or liquids, with applied voltages in excess of 100 kV. In this paper, the authors investigate possibilities to achieve sub-nanosecond breakdown at applied voltages below 7.5 kV in point-plane geometries. The setup consists of a pulser (risetime between 400 ps to 1 ns), 50-/spl Omega/ transmission line, axial needle-plane gap with outer coaxial conductor, and a 50-/spl Omega/ load line. The needle consists of tungsten and has a radius of curvature below 0.5 /spl mu/m. The constant system impedance of 50 /spl Omega/ (except in the vicinity of the gap) and a special transmission-line-type current sensors enables current and voltage measurements with a dynamic range covering several orders of magnitude, with temporal resolution down to 80 ps. For pulse amplitudes of 1.7 kV (which are doubled at the open gap before breakdown) delay times between start of the pulse and start of a measurable current flow (amplitude > several milliamperes) have a minimum of about 8 ns, at a pressure of 50 torr in argon. Voltages of 7.5 kV produce breakdowns with a delay of about 1 ns. With negative pulses applied to the tip, at an amplitude of 7.5 kV, breakdown is always observed during the rising part of the pulse, with breakdown delay times below 800 ps, at pressures between 1 and 100 torr. At lower pressure, a longer delay time (8 ns at 50 mtorr) is observed. They authors expect the breakdown mechanism to be dominated by electron field emission, but still influenced by gaseous amplification.

[PDF]

+ High speed optical diagnostics of an exploding wire fuse for power conditioning of explosive flux compression generators
  Giesselmann, M.; Heeren, T.; Neuber, A.; Walter, J.; Kristiansen, M.; Digest of Technical Papers, Pulsed Power Plasma Science, 2001. PPPS-2001. Volume 1, 17-22 June 2001 Page(s):102 - 105 vol.1
Abstract:  This paper presents high-speed optical diagnostics of an exploding wire fuse, which is used in the power conditioning system for an explosive flux compression generator. The images were taken using an IMACON(R) 790 high-speed framing camera utilizing a gated image intensifier tube. For the authors' measurements, the camera was operated in the high-speed multiple frame mode, yielding 8-10 sequential, 2 dimensional pictures with 100 ns between exposures.

[PDF]

+ High Voltage Testing of Capacitors
  "High Voltage Testing of Capacitors", Proceedings of 13th IEEE International Pulsed Power Conference, Las Vegas, Nevada, June 2001, p. 1563 (with S.I. Shkuratov, J.C. Dickens and E. Horrocks).
Abstract:  Not Available
+ Impact of helix geometry on MCG flux losses [magneto cumulative generators]
  Holt, T.; Neuber, A.; Dickens, J.; Kristiansen, M.; Digest of Technical Papers, Pulsed Power Plasma Science, 2001. PPPS-2001. Volume 2, 17-22 June 2001 Page(s):905 - 908 vol.2
Abstract:  Explosively driven magnetic flux compression has been the object of research for more than three decades. Recently heightened interest has been focused on the basic physical mechanisms that determine the performance of helical magneto cumulative generators (MCGs). Two single-pitch helical flux compression generators of different sizes have been tested using current-voltage probes and optical diagnostics. The main parameters used to characterize the experimental performance of the flux compression generators were the flux conservation and theoretical current gain of each type of generator. Helices with constant pitch and differing separation between wires as well as wires with different insulation thickness were tested and analyzed with respect to their flux conservation and theoretical current gain. Preliminary results show that the insulation thickness plays only a minor role for a change in flux conservation due to geometry in the range from 0.01 to 0.5 mm provided that no internal breakdown occurred. Additionally, the overall physical dimension of the generator was modified to allow for a substantial increase in initial inductance. The outer diameter of the generator armature was held constant at 1.5 inches and the coil diameter was varied from 2.6 to 3.5 inches (expansion ratio of 1.7 or 2.3, respectively). The results gained from the conservative expansion ratio of 1.7 were used as a base to compare to the generator performance at the more aggressive expansion ratio of 2.3. First results show that an expansion ratio of 2.3 produces viable results for a partially annealed Aluminum armature with a Gurney angle of approximately 15 degrees.

[PDF]

+ The Current Mode of Pulsed Power Generation in Moving Magnet Systems
  "The Current Mode of Pulsed Power Generation in Moving Magnet Systems", Proceedings of 13th IEEE International Pulsed Power Conference, Las Vegas, Nevada, June 2001, p. 228 (with S.I. Shkuratov, M. Kristiansen, J.C. Dickens, and J.C. Hernandez).
Abstract:  Not Available
+ Theoretical Treatment of Explosive Driven Ferroelectric Generators
  "Theoretical Treatment of Explosive Driven Ferroelectric Generators", Proceedings of 13th IEEE International Pulsed Power Conference, Las Vegas, Nevada, June 2001, p. 231 (with L.L. Altgilbers, Y. Tkach, S.I. Shkuratov, M. Kristiansen, J.C. Dickens, P.T. Tracy).
Abstract:  Not Available
+ Thermodynamic state of the magnetic flux compression generator volume
  Neuber, A.A.; Holt, T.A.; Dickens, J.C.; Kristiansen, M.; IEEE Conference Record - Abstracts, 2001 IEEE Conference on Pulsed Power Plasma Science, 17-22 June 2001 Page(s):151
Abstract:  Summary form only given, as follows.The knowledge of the thermodynamic state of the gas trapped in a helical flux compression generator is crucial for the assessment of flux loss due to internal electrical breakdown/arcing. Besides the helix deformation and armature deceleration at extremely high current amplitudes approaching 1 MA, the thermodynamic state of the shocked and compressed gas causes problems in the prediction of the generator output current vs. time towards the end of generator operation. Such a breakdown is experimentally detected as an abrupt change in the time derivative of the current waveform and it is easily distinguished from partial turn skipping by its sharper fall and non-periodic occurrence. The thermodynamic state of the generator was measured using primarily optical emission spectroscopy. Three main stages of operation are discussed: (1) The initial stage, which can be represented by a freely expanding armature, that shows fairly low gas temperatures, possibly as low as 2,000 K. (2) The intermediate stage during 14 to 4 microseconds before generator burnout that exhibits mainly an atomic copper line transition at about 0.8 eV. (3) The last few microseconds that reveal a highly compressed gas with temperatures of about 5,000 K and pressures of about 200 bar. Most experiments were conducted in air initially at STP, some results are given for SF6 initially at one atmosphere. In order to link the thermodynamic state to the breakdown sensitivity, additionally, simple conductivity measurements were conducted in current-free flux compression generator models

[PDF]

+ Transient Analysis of Copper Stator Turns in MFCG
  T. Benton, K.-T. Hsieh, F. Stefani, A. Neuber, and M. Kristiansen, “Transient Analysis of Copper Stator Turns in MFCG,“ Paper No. H.06, International Conference on Pulsed Power Applications, Gelsenkirchen, March 29-30, 2001.
Abstract:  Not Available
Publication Year:  2000
+ 3-D PIC Simulation of a Coaxial Vircator
  "3-D PIC Simulation of a Coaxial Vircator", 13th International Conference on High-Power Particle Beams, June 2000, Nagaoka, Japan (with W. Jiang, (Nagaoka University of Technology), and Jim Dickens.
Abstract:  Not Available
+ Dielectric/Gas Interface Breakdown Caused by High Power Microwave
  D. Hemmert, A. Neuber, H. Krompholz, L.L. Hatfield, and M. Kristiansen, “Dielectric/Gas Interface Breakdown Caused by High Power Microwaves," Third Directed Energy Symposium, November 1-2, 2000, Albuquerque, New Mexico.
Abstract:  Not Available
+ Energy Balance of Shock Wave Ferromagnetic Generators
  "Energy Balance of Shock Wave Ferromagnetic Generators", Proceedings of 12th Symposium on High Current Electronics, Tomsk, Russia, Sept. 24-29, 2000 (with S.I. Shkuratov and J. Dickens).
Abstract:  Not Available
+ Evaluation of a Solid State Opening Switch (SOS) Diode Pulser for use in a Electrochemical Reactor
  M. Giesselmann, M. Kristiansen, B. Grinstead, M. Wilson “Evaluation of a Solid State Opening Switch (SOS) Diode Pulser for use in a Electrochemical Reactor”, 2000 World Conference on Industrial Applications of Electrical Energy (An extended IEEE Industry Applications Society 35th Annual Meeting), Sheraton Roma Hotel, Rome Italy, October 8-12, 2000.
Abstract:  Not Available
+ Fundamental Studies of a Helical Magnetic Flux Compression Generator
  A. Neuber, J. Dickens, M. Giesselmann, B. Freeman, J. Rasty, H. Krompholz, and M. Kristiansen: Fundamental Studies of a Helical Magnetic Flux Compression Generator. Proceedings of the 13th International Conference on High-Power Particle Beams, June 25-30, 2000, Nagaoka, Japan.
Abstract:  Not Available
+ Fundamental studies of a simple helical magnetic flux compression generator
  Neuber, A.; Dickens, J.; Giesselmann, M.; Freeman, B.; Rasty, J.; Krompholz, H.; Kristiansen, M.; IEEE Conference Record - Abstracts. The 27th IEEE International Conference on Plasma Science, 2000. ICOPS 2000. 4-7 June 2000 Page(s):276
Abstract:  Summary form only given, as follows. The design of a helical flux compression generator, driven by 150 g of high explosives, for basic studies is presented and experimental results are discussed in comparison to numerical simulations. Simulation of the electric current output with the commercial circuit simulator PSPICE shows that this generator conserves the magnetic flux ideally in the low current mode, <30 kA. At current amplitudes in excess of 100 kA heating and melting of the single wound helix wire, AWG 12, limit the current flow. The volume between armature and stator is spectroscopically probed with fiber optics and valuable insight into the state of the shocked and compressed gas is gained. The same fiber optic probes are used to measure the velocity of the armature-stator contact along the generator axis. This contact velocity is largely affected by armature end effects, mainly due to the pressure loss at the detonator end. Both gas temperature and contact velocity have been successfully simulated with LS-DYNA3D, a three dimensional finite element hydrodynamic code. The generator's magnetic field structure is briefly discussed and magnetic field probe measurements are presented

[PDF]

+ Helical Flux Compression Generator for Basic Research
  A. Neuber, J. Dickens, M. Giesselmann, B. Freeman, P. Worsey, H. Krompholz, and M. Kristiansen, “Helical Flux Compression Generator for Basic Research,” 12th Symposium on High Current Electronics, September 25-29, 2000, Tomsk, Russia.
Abstract:  Not Available
+ High Power Microwave Window Breakdown under Vacuum and Atmospheric Conditions
  A. Neuber, D. Hemmert, J. Dickens, H. Krompholz, L. L. Hatfield, and M. Kristiansen: High Power Microwave Window Breakdown under Vacuum and Atmospheric Conditions. Proceedings of the SPIE conference, vol. 4031, pp. 90-98, Aerosense 2000, 24-28 April 2000, Orlando Florida.
Abstract:  Not Available
+ High-Power Microwave Generation by a Coaxial Vircator
  "High-Power Microwave Generation by a Coaxial Vircator", 13th International Conference on High-Power Particle Beams, June 2000, Nagaoka, Japan (with W. Jiang (Nagaoka University of Technology), and Jim Dickens).
Abstract:  Not Available
+ Pressure dependence of high power microwave solid dielectric/gas interface breakdown
  Neuber, A.; Hemmert, D.; Krompholz, H.; Hatfield, L.L.; Kristiansen, M.; 2000. ICOPS 2000. IEEE Conference Record - Abstracts. The 27th IEEE International Conference on Plasma Science, 4-7 June 2000 Page(s):124
Abstract:  The knowledge of the behavior of solid dielectric/gas interface breakdown caused by microwaves is crucial for developing new design methods for high power microwave windows. We investigate the physical mechanisms leading to breakdown for power levels on the order of 10 MW/cm2 at 2.85 GHz and gas pressures varying from 10-4 to 103 Torr. As an interface that is in widespread use, the focus was put on an alumina/air interface. Other gases are considered mainly for reference purposes. The high power microwaves are generated with a 4 MW magnetron having a 3.5 μs pulse width in conjunction with an S-band traveling wave resonator. This approach provides a power gain of maximum 25, sufficient to cause breakdown across the interface located in the pressure adjustable test region. The interface geometry comprises a thin ceramic alumina slab placed in the waveguide center. We ensure an almost purely tangential field and a localized breakdown by orienting the alumina slab normal to the direction of the wave propagation and making contact with two field enhancement tips placed in the middle of each waveguide broad wall

[PDF]

+ Studies on a Helical Magnetic Flux Compression Generator
  A. Neuber, J. Dickens, B. Freeman, P. Worsey, H. Krompholz, and M. Kristiansen: Studies on a Helical Magnetic Flux Compression Generator. Proceedings of the SAE Power Systems Conference, October 31-November 2, 2000, San Diego, CA.
Abstract:  Not Available
+ Sub-nanosecond gas breakdown phenomena in the voltage regime below 15 kV
  H. Krompholz, L.L. Hatfield, B. Short, M. Kristiansen, “Sub-nanosecond gas breakdown phenomena in the voltage regime below 15 kV”, EUROEM 2000, Edinburgh, UK, June 2000
Abstract:  Not Available
Publication Year:  1999
+ A Multidisciplinary University Research Program on Explosive Flux Compression Generators for Directed Energy Weapons
  "A Multidisciplinary University Research Program on Explosive Flux Compression Generators for Directed Energy Weapons", Proc. 12th IEEE International Pulsed Power Conference, Monterey, CA, June 27-30, 1999 (with Bruce Freeman and Paul Worsey).
Abstract:  Not Available
+ Characterization of the power handling capability of an S-band double disc gas cooled microwave window
  Neuber, A.; Ferguson, P.; Hendricks, K.; Hemmert, D.; Krompholz, H.; Hatfield, L.L.; Kristiansen, M.; IEEE Conference Record - Abstracts. 1999 IEEE International Conference on Plasma Science, 1999. ICOPS '99. 20-24 June 1999 Page(s):253
Abstract:  Summary form only given. The S-Band double disc microwave window comprises a rectangular waveguide to circular pillbox transition with two separate high purity, TiN coated alumina discs brazed into the pillbox. The geometrical dimensions are optimized for minimum electromagnetic wave reflection at a microwave frequency of 2.85 GHz in TE10 mode. The window is designed for power levels up to a few 100 MW with several microseconds pulse duration. Crucial for the power handling capability is the gas species and pressure of the gas flow applied for cooling the alumina discs

[PDF]

+ Development of improved triggered vacuum switches
  Warren, T.; Dickens, J.; Neuber, A.; Kristiansen, M.; Frazier, G.; McNab, I.R.; Digest of Technical Papers. 12th IEEE International Pulsed Power Conference, 1999. Volume 2, 27-30 June 1999 Page(s):1264 - 1267 vol.2
Abstract:  Triggered vacuum switches (TVS) are being evaluated for use in energizing electrical loads that require rapid and efficient switching of currents on command as well as the ability to interrupt at current zero crossing. Relatively few switching alternatives are available at the high currents (>250 kA) and voltages (>10 kV) needed. The TVSs used in recent pulsed power systems have demonstrated an ability to switch significant currents and interrupt at the zero current crossing, but they are not yet as effective as desired. In particular, higher current operation and faster dielectric recovery would be beneficial. The intent of this research is to expand the understanding of the physics of the vacuum switch (especially the opening phase) and to extend the operating parameters

[PDF]

+ Energy Efficiency Analysis of an Inductive Storage System
  J. Kim, J. Zhang, M. Giesselmann, J. Dickens, J. Mankowski, M. Kristiansen, “Energy Efficiency Analysis of an Inductive Storage System”, Proceedings of the 12th IEEE International Pulsed Power Conference, Monterey, California, June 27-30, 1999.
Abstract:  Not Available
+ Energy efficiency analysis of an inductive storage system
  Kim, J.; Zhang, J.; Giesselmann, M.; Dickens, J.; Mankowski, J.; Kristiansen, M.; Digest of Technical Papers. 12th IEEE International Pulsed Power Conference, 1999. Volume 2, 27-30 June 1999 Page(s):1445 - 1448 vol.2
Abstract:  In this paper, the simulation and evaluation of energy efficiency and voltage amplification in an inductive energy storage system with resistive, capacitive and diode loads is presented. A numerical simulation with Mathcad shows that by proper reduction of the storage energy inductance and of the exploding fuse interruption time, the energy efficiency and voltage amplification can be greatly improved

[PDF]

+ High voltage subnanosecond corona inception
  Mankowski, J.; Dickens, J.; Kristiansen, M.; Lehr, J.; Prather, W.; Gaudet, J.; Digest of Technical Papers. 12th IEEE International Pulsed Power Conference, 1999. Volume 2, 27-30 June 1999 Page(s):1392 - 1395 vol.2
Abstract:  Corona discharges in ultra-wideband radiating systems can have adverse effects on performance such as reflection, phase dispersion, and significant power losses. A test-bed has been assembled to experimentally observe corona created by voltage pulses similar to ultra-wideband systems. The current work involves the voltage attenuation of an incident pulse after propagation through a self-initiated corona and relative measurements of visible light emission from the photoionization produced during streamer development. Several gas dielectrics, including ambient air, N2, H2 , and SF6, were tested

[PDF]

+ High-Power Microwave Generation by Coaxial Vircator
  "High-Power Microwave Generation by Coaxial Vircator", Proc. 12th IEEE International Pulsed Power Conference, Monterey, CA, June 27-30, 1999 (with W. Jiang, K. Woolverton, J. Dickens).
Abstract:  Not Available
+ Influence of the microwave magnetic field on high power microwave window breakdown
  Hemmert, D.; Neuber, A.; Dickens, J.; Krompholz, H.; Hatfield, L.L.; Kristiansen, M.; IEEE Conference Record - Abstracts. 1999 IEEE International Conference on Plasma Science, 1999. ICOPS '99. 20-24 June 1999 Page(s):229
Abstract:  Summary form only given. Effects of the microwave magnetic field on window breakdown are investigated at the upstream and downstream side of a dielectric interface. Simple trajectory calculations of secondary electrons in an RF field show significant forward motion of electrons parallel to the microwave direction of propagation. The Lorentz-force due to the microwave magnetic field on high-energy secondary electrons might substantially influence the standard multipactor mechanism. As a result, the breakdown power level for the downstream side of a window would be higher than for the upstream side. This hypothesis was tested utilizing an S-band traveling wave resonant ring, powered by a 3 MW magnetron at 2.85 GHz, leading to a total power greater than 60 MW. Breakdown was studied on an interface geometry consisting of a thin alumina slab in the waveguide, oriented normal to the microwave propagation direction

[PDF]

+ Optical Diagnostics on Helical Flux Compression Generators
  A. Neuber, J. Dickens, H. Krompholz, and M. Kristiansen: Optical Diagnostics on Helical Flux Compression Generators. 12th IEEE Int. Pulsed Power Conference, Monterey, CA (1999)
Abstract:  Not Available
+ Pulse Power Conditioning with a Transformer for an Inductive Energy Storage System
  M. Giesselmann, J. Zhang, T. Heeren, E. Kristiansen, J. Dickens, D. Castro, D. Garcia, M. Kristiansen, “Pulse Power Conditioning with a Transformer for an Inductive Energy Storage System”, Proceedings of the 12th IEEE International Pulsed Power Conference, Monterey, California, June 27-30, 1999.
Abstract:  Not Available
+ Pulsed Power Generation Using Ferromagnetic Circuits
  "Pulsed Power Generation Using Ferromagnetic Circuits", Proc. 12th IEEE International Pulsed Power Conference, Monterey, CA, June 27-30, 1999 (with S.I. Shkuratov, J. Dickens, L.L. Hatfield, and R. Martin).
Abstract:  Not Available
+ Pulsed, High Energy Testing of Resistors
  "Pulsed, High Energy Testing of Resistors", Proc. 12th IEEE International Pulsed Power Conference, Monterey, CA, June 27-30, 1999 (with S.I. Shkuratov, J. Dickens, L.L. Hatfield, and E. Horrocks).
Abstract:  Not Available
+ Simulation, Design and Test of a MOV Pulse Shaping Device for High Power Microwave Generators
  M. Giesselmann, T. Heeren, E. Kristiansen, J. Dickens, D. Castro, D. Garcia, M. Kristiansen, “Simulation, Design and Test of a MOV Pulse Shaping Device for High Power Microwave Generators”, Proceedings of the 12th IEEE International Pulsed Power Conference, Monterey, California, June 27-30, 1999.
Abstract:  Not Available
+ Surface flashover of dielectrics immersed in super-cooled liquid nitrogen
  Butcher, M.; Neuber, A.; Krompholz, H.; Hatfield, L.L.; Kristiansen, M.; Digest of Technical Papers. 12th IEEE International Pulsed Power Conference, 1999. Volume 1, 27-30 June 1999 Page(s):450 - 453 vol.1
Abstract:  In a fast coaxial setup, dielectric test sample and electrodes are immersed in super-cooled liquid nitrogen with a temperature near 68 K, and the flashover development process is characterized using fast optical and electrical diagnostics with nanosecond time resolution. The measured breakdown voltage as a function of consecutive flashover shots reaches its peak around the second flashover and declines to a constant value. This voltage is initially about 50% of the volume breakdown voltage in liquid nitrogen and drops to about 20% after the sample has been conditioned. Two materials, Lexan and alumina, were tested in the system and showed quite similar breakdown voltages, but alumina exhibited much more severe surface damage. The time resolved electrical diagnostic revealed three phases in the temporal development of the current. Phase 1 is a rapid rise to the mA regime that is probably associated with field emission. Phase 2 contains several pre-breakdown spikes with current amplitudes of less than 5 mA and duration of typically 20 nanoseconds that form and collapse over a period of tens to a couple hundred nanoseconds. Finally, Phase 3, is characterized by a rapid ionization across the surface with a current rise that covers 4 orders of magnitude in a few nanoseconds

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+ The design of a compact pulse transformer
  Zhang, J.; Dickens, J.; Giesselmann, M.; Kim, J.; Kristiansen, E.; Mankowski, J.; Garcia, D.; Kristiansen, M.; Digest of Technical Papers. 12th IEEE International Pulsed Power Conference, 1999. Volume 2, 27-30 June 1999 Page(s):704 - 707 vol.2
Abstract:  To improve the pulse shape and to obtain μs order pulse duration on a diode load in an inductive energy storage system, an oil-submerged compact pulse transformer with diameter of 20 cm and length of 70 cm has been designed and tested. From theoretical calculations, the parameters with primary inductance Lp=3.4 μH, secondary inductance Ls=90 μH, and coupling coefficient K=0.772 are obtained. To prevent breakdown, a conical secondary design is adopted. Under the condition of 500 kV operation voltage, the maximum electric field in the transformer is 205 kV/cm (in oil). The axial voltage distribution on the secondary is linear. Experiments have been done to test the insulation, the mechanical force and the coupling coefficient. The test results are consistent with the design parameters

[PDF]

+ The Design of a compact Pulse Transformer
  J. Zhang, J. Dickens, M. Giesselmann, J. Kim, E. Kristiansen, J. Mankowski, D. Garcia, M. Kristiansen, “The Design of a compact Pulse Transformer”, Proceedings of the 12th IEEE International Pulsed Power Conference, Monterey, California, June 27-30, 1999.
Abstract:  Not Available
+ The Role of Outgassing in Surface Flashover under Vacuum
  A. Neuber, J. Dickens, H. Krompholz, and M. Kristiansen: The Role of Outgassing in Surface Flashover under Vacuum. 12th IEEE Int. Pulsed Power Conference, Monterey, CA (1999), invited.
Abstract:  Not Available
Publication Year:  1998
+ Breakdown of dielectric/vacuum interfaces caused by high power microwaves
  Neuber, A.; Dickens, J.; Hemmert, D.; Krompholz, H.; Hatfield, L.L.; Kristiansen, M.; IEEE Conference Record - Abstracts. 1998 IEEE International on Plasma Science, 1998. 25th Anniversary. 1-4 June 1998 Page(s):205
Abstract:  Summary form only given. Physical mechanisms leading to microwave breakdown on dielectric/vacuum interfaces are investigated for power levels on the order of 100 MW at 2.85 GHz. A 3 MW magnetron with 3.5 μs pulse width, is coupled to an S-band traveling wave resonator which is kept at a pressure of 10-8 Torr. The investigation is focused on an interface geometry comprising a thin dielectric polymer slab in the waveguide, oriented vertical to the direction of wave propagation, and two field enhancement tips placed in the middle of each waveguide broad wall. This ensures an almost purely tangential field at the interface surface and a localized breakdown

[PDF]

+ High voltage subnanosecond dielectric breakdown
  Mankowski, J.; Dickens, J.; Kristiansen, M.; IEEE Conference Record - Abstracts. 1998 IEEE International on Plasma Science, 1998. 25th Anniversary. 1-4 June 1998 Page(s):270
Abstract:  Summary form only given, as follows. Present day ultra-wideband (UWB) radiation sources a produce Megavolt pulses at 100's of picosecond (ps) risetimes. Empirical data on the breakdown characteristics for dielectric media at these short time lengths and high voltages are either extremely limited or non-existent. In support of the design of these UWB sources, we are investigating the breakdown characteristics, at these voltages and time lengths, of several liquids and gases. These include air, N2, H2, He, SF6, and transformer oil. The two voltage sources used in the experiments are capable of delivering 400 and 700 kV with a 400 ps risetime into an open load. These pulses are applied to the test gap area, capable of housing various gases and liquids at pressures from less than 1 to 150 atm. An empirical relationship of E-field versus breakdown time for the observed dielectrics is presented. Several other breakdown phenomena at these fast risetimes are observed. Dielectric breakdown strength dependence on polarity is investigated. Streak camera images of arc formation are captured, providing information on gap closure velocity. Also observed is the effect of ultraviolet radiation on the statistical lag time of breakdown for gas dielectrics at various pressures

[PDF]

+ Simulation, Design and Construction of a Pulsed Power Supply for High Power Microwaves Using Explosively Driven Magnetic Flux Compression
  M. Kristiansen, J. Dickens, T. Hurtig, M. Giesselmann, E. Kristiansen, “Simulation, Design and Construction of a Pulsed Power Supply for High Power Microwaves Using Explosively Driven Magnetic Flux Compression”, Proceedings of the 1998 MegaGauss Conference, ISBN 982-256-016-5, Tallahassee, Florida, October 18 – 23, 1998, p. 425…428.
Abstract:  Not Available
Publication Year:  1997
+ A subnanosecond high voltage pulser for the investigation of dielectric breakdown
  Mankowski, J.; Dickens, J.; Kristiansen, M.; Pulsed Power Conference, 1997. 1997 11th IEEE International Digest of Technical Papers. Volume 1, 29 June-2 July 1997 Page(s):549 - 554 vol.1
Abstract:  A high voltage, sub-nanosecond pulser is designed and built for the purposes of investigating dielectric breakdown. The requirement for the pulser is a voltage pulse of several hundred kilovolts, pulsewidth less than a few nanoseconds, and a risetime <400 psec. This is achieved by using pulse sharpening techniques on the output of a 500 kV Marx bank. Originally designed to stimulate a lightning strike, the voltage waveform from the Marx generator has a slow decay time of tens of μsec. In order to obtain a more desirable pulse, the Marx bank is modified. By removing a lumped-element resistor a higher peak output voltage with a faster risetime can be obtained. Circuit simulations have shown the capability of achieving an 800 kV output in less than 40 nsec to a charging (pulse forming) line. The 50 Ω impedance, oil-filled, pulse forming line consists of a peaking gap and pulse slicing gap. The peaking gap decreases the risetime of the applied pulse down to about 300 psec. The pulse slicing gap is included to short the voltage applied to the delay line and test chamber

[PDF]

+ Computer Simulation of Coaxial Vircators
  "Computer Simulation of Coaxial Vircators", SPIE Conf., San Diego, CA, July 27-August 1, 1997, (with Kevin Woolverton and L.L. Hatfield).
Abstract:  Not Available
+ Diode Polarity experiments on a Coaxial Vircator
  "Diode Polarity experiments on a Coaxial Vircator", Proc. 11th IEEE Int’l. Pulsed Power Conf., Baltimore, MD, June 29-July 2, 1997 (with Kevin Woolverton and L.L. Hatfield).
Abstract:  Not Available
+ Evaluation of a Russian SOS Diode for use in a Compact Modulator System
  J. Dickens, M. Kristiansen, M. Giesselmann and J.G. Kim, "Evaluation of a Russian SOS Diode for use in a Compact Modulator System", Proceedings of the 11th IEEE International Pulsed Power Conference, Baltimore, Maryland, June 29 - July 02, 1997.
Abstract:  Not Available
+ Evaluation of a Russian SOS Diode for Use in a Compact Modulator System
  "Evaluation of a Russian SOS Diode for Use in a Compact Modulator System", Proc. 11th IEEE Int’l. Pulsed Power Conf., Baltimore, MD June 29-July 2, 1997 (with J. Dickens).
Abstract:  Not Available
+ Feasibility of Permanent Magnet Design for High Power Microwave Generators
  "Feasibility of Permanent Magnet Design for High Power Microwave Generators", Eight National Conference on High Power Microwave Technologies”, April 8-10, 1997 (with F.J. Agee and J. Gaudet).
Abstract:  Not Available
+ High voltage subnanosecond dielectric breakdow - 1997
  Mankowski, J.; Hatfield, L.; Kristiansen, M.; Agee, F.J.; Lehr, J.M.; Wells, J.; IEEE Conference Record - Abstracts., 1997 IEEE International Conference on Plasma Science, 1997. 19-22 May 1997 Page(s):317 - 318
Abstract:  Summary form only given. Present day ultra wideband radiation sources produce megavolt pulses at 100's of picosecond pulsewidths. Empirical data on the breakdown characteristics for dielectric media at these short time lengths and high voltages are either extremely limited or non-existent. In support of the design of these ultra wideband sources, we are investigating the breakdown characteristics, at these voltages and time lengths, of several liquids and gases. These include air, N2, H2, He, SF6, transformer oil, and freon-12

[PDF]

+ Window and Cavity Breakdown caused by High Power Microwaves
  A. Neuber, J. Dickens, D. Hemmert, H. Krompholz, L. L. Hatfield, and M. Kristiansen: Window and Cavity Breakdown caused by High Power Microwaves. 11th IEEE Int. Pulsed Power Conf., Baltimore (1997)
Abstract:  Not Available
+ Window and Cavity Breakdown caused by High Power Microwaves
  A. Neuber, J. Dickens, D. Hemmert, H. Krompholz, L. L. Hatfield, and M. Kristiansen: Window and Cavity Breakdown caused by High Power Microwaves. IEEE International Conference on Plasma Science, San Diego (1997)
Abstract:  Not Available
+ Window and Cavity Breakdown caused by High Power Microwaves
  A. Neuber, J. Dickens, D. Hemmert, H. Krompholz, L. L. Hatfield, and M. Kristiansen: Window and Cavity Breakdown caused by High Power Microwaves. International Workshop on High Power Microwave Generation and Pulse Shortening, Edinburgh UK (1997)
Abstract:  Not Available
Publication Year:  1996
+ Breakdown at window interfaces caused by high power microwave fields
  J.C. Dickens, J. Elliott, L.L. Hatfield, M. Kristiansen, H. Krompholz, “Breakdown at window interfaces caused by high power microwave fields”, International Symposium on Optical Science, Engineering, and Instrumentation - SPIE’s Annual Meeting, Denver, CO, August 4-9, 1996, published in SPIE proceedings Volume 2843, “Intense Microwave Pulses IV”, pg.153
Abstract:  Not Available
+ Coaxial Vircator Source Development
  "Coaxial Vircator Source Development", 11th Int’l. Conf. On High Power Particle Beams”, Prague, Czech Republic, June 10-14, 1996 (with Kevin Woolverton and L.L. Hatfield)
Abstract:  Not Available
+ Compact Modulator Using Inductive Energy Storage and a Solid State Opening Switch
  "Compact Modulator Using Inductive Energy Storage and a Solid State Opening Switch", 1996 22nd International Power Modulator Symposium, Boca Raton, FL, June 24-27, 1996 (with James C. Dickens and John Bridges).
Abstract:  Not Available
+ Dielectric Surface Flashover with UV and Plasma Background
  F. Hegeler, H. Krompholz, L.L. Hatfield and M. Kristiansen, "Dielectric Surface Flashover with UV and Plasma Background," Symposium on “Physics, Diagnostics, and Application of Pulsed High Energy Density Plasma as an Extreme State”, Nagoya, Japan, May 1996, Japanese National Institute for Fusion Science Proceedings Series # 26 (NIFS-PROC-26, ISSN 0915-6348), pg. 104-114
Abstract:  Not Available
Publication Year:  1995
+ Central University Research Consortium
  "Central University Research Consortium", 10th IEEE International Pulsed Power Conference, Albuquerque, NM, July 10-13, 1995 (with Edl Schamiloglu,, Ron Gilgenbach, and Jim Benford).
Abstract:  Not Available
+ Experimental Results from a Coaxial Virtual Cathode Oscillator
  "Experimental Results from a Coaxial Virtual Cathode Oscillator", 10th IEEE International Pulsed Power Conference, Albuquerque, NM, July 10-13, 1995 (with Mark Crawford and L.L. Hatfield).
Abstract:  Not Available
+ Insulator Development for Advanced Simulators
  "Insulator Development for Advanced Simulators", 10th IEEE International Pulsed Power Conference, Albuquerque, NM, July 10-13, 1995 (with F.K. Childers, P.S. Sincerny, S.R. Ashby, L. Mandelcorn, and M. Mendelsohn, and T.G. Engel).
Abstract:  Not Available
+ Insulator Surface Breakdown in a Simulated Low Earth Orbit Environment
  F. Hegeler, H. Krompholz, L. Hatfield, M. Kristiansen, “Insulator Surface Breakdown in a Simulated Low Earth Orbit Environment”, Proc. of the 10th IEEE Pulsed Power Conf., Albuquerque, NM, July 1995, pg. 568
Abstract:  Not Available
+ Insulator Surface Flashover with UV and Plasma Background and External Magnetic Field
  F. Hegeler, H. Krompholz, L.L. Hatfield, M. Kristiansen, “Insulator Surface Flashover with UV and Plasma Background and External Magnetic Field”, Proc. of “Conference on Electrical Insulation and Dielectric Phenomena (CEIDP)”, Virginia Beach, Va, Oct. 22-25, 1995 IEEE Catalog Nr. 95CH35842), pg. 171
Abstract:  Not Available
+ Low Frequency Inductive Heating of a Rigid Track During Track Laying
  "Low Frequency Inductive Heating of a Rigid Track During Track Laying", Conf. Record of the 1995 IEEE Industry Applications Society, 30th IAS Meeting, Orlando, FL, Oct. 8-12, 1995 (with B. Miedzinski, Z. Okraszewski, and A. Szymanski).
Abstract:  Not Available
+ Modeling of Graphite Electrode Failure in High Power Spark Gaps
  "Modeling of Graphite Electrode Failure in High Power Spark Gaps", 10th IEEE International Pulsed Power Conference, Albuquerque, NM, July 10-13, 1995 (with M. Wofford and M. Baker).
Abstract:  Not Available
+ Nanosecond Electron Beam Controlled Switching
  "Nanosecond Electron Beam Controlled Switching", 10th IEEE International Pulsed Power Conference, Albuquerque, NM, July 10-13, 1995 (with J.M. Awrach, M.C. Baker, L.L. Hatfield, S. Gangopadhyay, and K. Zinsmeyer).
Abstract:  Not Available
+ Plume Model of Hall Effect Plasma Thrusters with Temporal Consideration
  "Plume Model of Hall Effect Plasma Thrusters with Temporal Consideration", XXIV International Electric Propulsion Conference, Moscow, Russia, Sept. 19-23, 1995 (with J.C. Dickens, E. O’Hair and M. Kristiansen).
Abstract:  Not Available
+ Pulsed Electrical Breakdown in Water
  "Pulsed Electrical Breakdown in Water", 10th IEEE International Pulsed Power Conference, Albuquerque, NM, July 10-13, 1995 (with D. Lojewski and T.G. Engel).
Abstract:  Not Available
+ Pulsed Power Applications
  "Pulsed Power Applications", IEEJ/1995 International Power Electronic Conference, April 3-7, 1995, Yokohama, Japan.
Abstract:  Not Available
Publication Year:  1994
+ Compact 500 kV Pulser
  "Compact 500 kV Pulser," 21st Power Modulator Sympsoium, June 28-30, 1994, Costa Mesa, California (with T.G. Engel and J. Bridges).
Abstract:  Not Available
+ Comparison between Simulation and Experiment on a Coaxial Vircator High-Power Microwave System
  "Comparison between Simulation and Experiment on a Coaxial Vircator High-Power Microwave System", 10th International Conference on High Power Particle Beams, June 20-24, 1994, San Diego, CA (with Mark Crawford).
Abstract:  Not Available
+ Comparisons Between Simulation and Experiment on a Coaxial Vircator High-Power Microwave System
  "Comparisons Between Simulation and Experiment on a Coaxial Vircator High-Power Microwave System", 10th International Conference on High Power Particle Beams, San Diego, CA, June 20-24, 1994 (with M. Crawford and L.L. Hatfield).
Abstract:  Not Available
+ Mass Erosion and Surface Voltage Holdoff Recovery of Insulators Used In A High Current, High Vacuum Surface Discharge Switch
  "Mass Erosion and Surface Voltage Holdoff Recovery of Insulators Used In A High Current, High Vacuum Surface Discharge Switch", 21st Power Modulator Symposium, June 28-30, 1994, Costa Mesa, California, (with T.G. Engel, S.L. Wester, and L.L. Hatfield).
Abstract:  Not Available
+ Mass Erosion and Surface Voltage Holdoff Recovery of Insulators Used in a High Current, High Vacuum Surface Discharge Switch
  "Mass Erosion and Surface Voltage Holdoff Recovery of Insulators Used in a High Current, High Vacuum Surface Discharge Switch", XVIth International Symposium on Discharges and Electrical Insulation in Vacuum, May 23-30, 1994, St. Petersburg/Moscow, Russia (with T.G. Engel, S.L. Wester, and L.L. Hatfield).
Abstract:  Not Available
+ Outgassing and Plasma Development in the Early Phase of Dielectric Surface Flashover in Vacuum
  G. Masten, T. Mueller, H. Krompholz, F. Hegeler, L.L. Hatfield, M. Kristiansen, "Outgassing and Plasma Development in the Early Phase of Dielectric Surface Flashover in Vacuum", Proc. of 10th International Conference on High Power Particle Beams ("Beams '94"), San Diego, CA, June 20-24, 1994
Abstract:  Not Available
+ Results from a Coaxial Vircator: Experiment and Simulation
  "Results from a Coaxial Vircator: Experiment and Simulation", Seventh National Conference on High Power Microwave Technology, Oct. 31 - Nov. 4, 1994, Monterey, CA (with Mark Crawford).
Abstract:  Not Available
+ The Early Phase of Dielectric Surface Flashover in a Simulated Low Earth Orbit Environment
  F. Hegeler, H. Krompholz, L.L. Hatfield, M. Kristiansen, "The Early Phase of Dielectric Surface Flashover in a Simulated Low Earth Orbit Environment", Proc. of 1994 Conf. on Electrical Insulation and Dielectric Phenomena (CEIDP), Arlington, TX, Oct. 1994, p. 594
Abstract:  Not Available
Publication Year:  1993
+ A Compact 500 kV Nanosecond Pulser
  "A Compact 500 kV Nanosecond Pulser", 9th IEEE Pulsed Power Conference, Albuquer­que, NM, June 21-23, 1993 (with T.G. Engel).
Abstract:  Not Available
+ Cathode Erosion Research on Medium to High Power Arcjet Thrusters
  "Cathode Erosion Research on Medium to High Power Arcjet Thrusters", 23rd International Electric Propulsion Conference, Seattle, WA, Sept. 13-16, 1993 (with W.J. Harris, E.A. O’Hair, and L.L. Hatfield).
Abstract:  Not Available
+ Cylindrically-Symmetric Virtual Cathode Oscillator High-Power Microwave Source
  "Cylindrically-Symmetric Virtual Cathode Oscillator High-Power Microwave Source", 9th IEEE Pulsed Power Conference, Albuquerque, NM, June 21-23, 1993 (with Mark Crawford and L.L. Hatfield).
Abstract:  Not Available
+ Electrode Performance of a Three Electrode, Triggered, High Energy Spark Gap Switch
  "Electrode Performance of a Three Electrode, Triggered, High Energy Spark Gap Switch", 9th IEEE Pulsed Power Conference, Albuquerque, NM, June 21-23, 1993 (with J.C. Dickens and T.G. Engel).
Abstract:  Not Available
+ Electron-Beam Controlled Switching Using Quartz and Polycrystalline ZnSe
  "Electron-Beam Controlled Switching Using Quartz and Polycrystalline ZnSe", 9th IEEE Pulsed Power Conference, Albuquerque, NM, June 21-23, 1993 (with W. Jiang, K. Zinsmeyer, M. Less and K.H. Schoenbach).
Abstract:  Not Available
+ Experimental Investigation of the Early Phase of Dielectric Surface Flashover in Vacuum
  F. Hegeler, G. Masten, G. Leiker, H. Krompholz, M. Kristiansen, "Experimental Investigation of the Early Phase of Dielectric Surface Flashover in Vacuum", Proc. 9th IEEE International Pulsed Power Conference, Albuquerque, NM, USA, 1993, p. 237
Abstract:  Not Available
+ Insulator Degradation Produced by High Current High Vacuum Surface Discharges
  "Insulator Degradation Produced by High Current High Vacuum Surface Discharges", 9th IEEE Pulsed Power Conference, Albuquerque, NM, June 21-23, 1993 (with S.L. Wester and T.G. Engel).
Abstract:  Not Available
Publication Year:  1992
+ A Status Report on Project Hercules
  D.L. Loree, M. Kristiansen, M. Giesselmann, and D. Larson, "A Status Report on Project Hercules", Sixth Symposium on Electromagnetic Launch Technology (EML), Austin, Texas, April 28-30, 1992.
Abstract:  Not Available
+ Anode Arc Motion in High Power Arcjets
  "Anode Arc Motion in High Power Arcjets", AIAA 28th Joint Propulsion Conference and Exhibit, Nashville, TN, July 6-8, 1992, paper AIAA 92-3838 (with W.J. Harris, E.A. O'Hair, and L.L. Hatfield).
Abstract:  Not Available
+ Characterization of a Novel Single-Gap Transformer Coupled L-C Generator
  "Characterization of a Novel Single-Gap Transformer Coupled L-C Generator", 20th International Power Modulator Symposium, Myrtle Beach, SC, June 23-25, 1992. (with T.G. Engel).
Abstract:  Not Available
+ Comparison of Erosion of Various Cathode Materials in a 30 kWe Class Arcjet
  "Comparison of Erosion of Various Cathode Materials in a 30 kWe Class Arcjet", AIAA 28th Joint Propulsion Conference and Exhibit, Nashville, TN,, July 6-8, 1992, paper AIAA 92-3839 (with W.J. Harris, E.A. O'Hair, and L.L. Hatfield).
Abstract:  Not Available
+ Computer Assisted Diagnostics on a High-Power Microwave System
  "Computer Assisted Diagnostics on a High-Power Microwave System", 9th International Conference on High Power Particle Beams, Washington, DC, May 25-29, 1992 (with M. Crawford S. Calico and L. Hatfield.
Abstract:  Not Available
+ Insulator and Electrode Mass Erosion and Surface Voltage Holdoff Recovery for Transient, High Current Surface Discharges
  "Insulator and Electrode Mass Erosion and Surface Voltage Holdoff Recovery for Transient, High Current Surface Discharges", 6th Electromagnetic Launch Technology, April 28-30, 1992, Austin, TX (with T.G. Engel and J.C. Dickens).
Abstract:  Not Available
+ Physical Model and Experimental Results of Cathode Erosion Related to Power Supply Ripple
  "Physical Model and Experimental Results of Cathode Erosion Related to Power Supply Ripple", AIAA 28th Joint Propulsion Conference and Exhibit, Nashville, TN, July 6-8, 1992, paper AIAA 92-3837 (with W.J. Harris, E.A. O'Hair, and L.L. Hatfield).
Abstract:  Not Available
+ Spark Gap Ignitor Studies on a Pulsed Power Ignitron
  D.L. Loree, M. Giesselmann, and M. Kristiansen, "Spark Gap Ignitor Studies on a Pulsed Power Ignitron", XVth International Symposium on Discharges and Electrical Insulation in Vacuum, Darmstadt, Germany, Sep. 6-10, 1992.
Abstract:  Not Available
+ Using Magnetic Pulse Shaping to Reduce Spark-Gap Losses and Electrode Erosion
  "Using Magnetic Pulse Shaping to Reduce Spark-Gap Losses and Electrode Erosion", 20th International Power Modulator Symposium, Myrtle Beach, SC, June 23-25, 1992. (with M. Wofford and M. Baker).
Abstract:  Not Available
Publication Year:  1991
+ A simple computer simulation of magnetic inhibition of dielectric surface flashover
  M. Lehr, H. Krompholz, M. Kristiansen, "A simple computer simulation of magnetic inhibition of dielectric surface flashover", Proc. Eighth IEEE International Pulsed Power Conference, San Diego, Ca., June 1991, p. 332
Abstract:  Not Available
+ Acoustical Resonant Behavior and V-I Curves for a 30-kWe Nitrogen Arcjet
  "Acoustical Resonant Behavior and V-I Curves for a 30-kWe Nitrogen Arcjet", AIDAA/AIAA/DGLR/JSASS 22nd International Electric Propulsion Conference, Viareggio, Italy, October 14-17, 1991 (with M. Grimes, W. Harris, E. O'Hair, L. Hatfield and M. Baker).
Abstract:  Not Available
+ Characterization and Study of Light Degradation Effects in ECR a-Si:H,Cl Films
  "Characterization and Study of Light Degradation Effects in ECR a-Si:H,Cl Films", International Conference on Stability of a-Si:H, Denver, CO, Feb. 20­23, 1991 (with C.P. Palsule, S. Gangopadhyay, C. Young, and T. Trost).
Abstract:  Not Available
+ Continuous Characteristic V-I Curves for a 30 kWe Nitrogen Arcjet
  "Continuous Characteristic V-I Curves for a 30 kWe Nitrogen Arcjet", 27th Joint Propulsion Conference and Exhibit, Sacramento, CA, June 24-27, 1991 (with William J. Harris, Montgomery Grimes, Edgar A. O'Hair, and Lynn L. Hatfield).
Abstract:  Not Available
+ Effect of Current Ripple on Cathode Erosion in 30 kWe Arcjets
  "Effect of Current Ripple on Cathode Erosion in 30 kWe Arcjets", 27th Joint Propulsion Conference and Exhibit, Sacramento, CA, June 24-27, 1991 (with William J. Harris, Montgomery Grimes, Edgar A. O'Hair, and Lynn L. Hatfield).
Abstract:  Not Available
+ High Current Electron Emitters
  "High Current Electron Emitters", International School of Plasma Physics, 469, Varenna, Italy, Villa Monastero, Sept. 9-20, 1991.
Abstract:  Not Available
+ Pulsed Microwave Breakdown of Solid Dielectric/Gas Interfaces
  "Pulsed Microwave Breakdown of Solid Dielectric/Gas Interfaces", International Conference on Phenomena in Ionized Gases, Pisa, Italy, July 8-12, 1991 (with M. Crawford, S. Calico and L. Hatfield).
Abstract:  Not Available
+ Pulsed Power Sources and Circuits for High Power Microwave Devices
  "Pulsed Power Sources and Circuits for High Power Microwave Devices", International School of Plasma Physics, 445, Varenna, Italy, Villa Monastero, Sept. 9-­20, 1991.
Abstract:  Not Available
+ Pulsed Vacuum Diode Diagnostics at the Texas Tech University High Power Microwave Facility
  "Pulsed Vacuum Diode Diagnostics at the Texas Tech University High Power Microwave Facility", 8th Pulsed Power Conference, San Diego, CA, June 17-19, 1991 (Mark Crawford and Steve Calico).
Abstract:  Not Available
+ Pulsed Vacuum Diode Diagnostics at the Texas Tech University High Power Microwave Facility
  M. Crawford, S. Calico, M. Kristiansen, H. Krompholz, "Pulsed Vacuum Diode Diagnostics at the Texas Tech University High Power Microwave Facility", Proc. Eighth IEEE International Pulsed Power Conference, San Diego, Ca., June 1991, p. 602
Abstract:  Not Available
+ Recent Advances in High Power Ignitron Development
  D.L. Loree, M. Giesselmann, M. Kristiansen, A. Shulski, R. Kihara, "Recent Advances in High Power Ignitron Development", 19th Power Modulator Symposium, June 26-28, 1990, San Diego, Ca., IEEE Transactions on Electron Devices, Vol. 30, No. 4, p. 720…725, April 1991.
Abstract:  Not Available
+ Recombination Studies of a High Current Ignitron
  D.L. Loree, M. Giesselmann, E. Loree, M. Kristiansen, and A. Shulski, "Recombination Studies of a High Current Ignitron", 8th IEEE International Pulsed Power Conference", June 15-19, 1991, San Diego, California.
Abstract:  Not Available
+ Simulation of the Low Earth Orbit for the Study of Pulsed Insulator Flashover and Degradation
  M. Mayerchak, M. Kristiansen, H. Krompholz, L.L. Hatfield, G. Leiker, C. Young, "Simulation of the Low Earth Orbit for the Study of Pulsed Insulator Flashover and Degradation", Proc. Eighth IEEE International Pulsed Power Conference, San Diego, Ca., June 1991, p. 1041
Abstract:  Not Available
+ Static Pressure Measurements in a 30 kWe Class Arcjet
  "Static Pressure Measurements in a 30 kWe Class Arcjet", 27th Joint Propulsion Conference and Exhibit, Sacramento, CA, June 24-27, 1991 (with William J. Harris, Montgomery Grimes, Edgar A. O'Hair, and Lynn L. Hatfield).
Abstract:  Not Available
+ The Erosion Performance of Graphite Electrodes in High Current, High Coulomb, Spark Gaps
  "The Erosion Performance of Graphite Electrodes in High Current, High Coulomb, Spark Gaps", 8th Pulsed Power Conference, San Diego, CA, June 17-19, 1991 (with A.L. Donaldson).
Abstract:  Not Available
Publication Year:  1990
+ Characterization of a-Si:H, Cl and a-SiC:H Films prepared by Electron Cyclotron Resonance Plasma
  "Characterization of a-Si:H, Cl and a-SiC:H Films prepared by Electron Cyclotron Resonance Plasma", Proc. Materials Research Society, Amorphous Silicon Technology - 1990, 92, 627 (with S. Gangopadhyay, T. Trost, C. Young, P. Zheng, C. Palsule and M. Pleit).
Abstract:  Not Available
+ Ignitron Research at Texas Tech University
  D.L. Loree, M. Giesselmann, and M. Kristiansen, "Ignitron Research at Texas Tech University," International Magnetic Pulse Compression Workshop, Granlibakken Conference Center, Lake Tahoe, California, Feb. 12-14, 1990.
Abstract:  Not Available
+ Magnetic Field Effects on Dielectric Surface Flashover
  M. Lehr, R. Korzekwa, H. Krompholz, M. Kristiansen, "Magnetic Field Effects on Dielectric Surface Flashover", Proc. 14th International Symposium on Discharges and Electrical Insulation in Vacuum, Santa Fe, NM, Sep. 17-20, 1990, p. 347
Abstract:  Not Available
+ Plasma Diagnostics for High Power Ignitron Development
  D.L. Loree, M. Giesselmann, M. Kristiansen and A. Shulski, "Plasma Diagnostics for High Power Ignitron Development", 5th Symposium on Electromagnetic Launch Technology (EML), April 2-5, 1990, Destin, Florida.
Abstract:  Not Available
+ Surface Discharge Switch Design: The Critical Factor
  "Surface Discharge Switch Design: The Critical Factor", Proc. 19th Power Modulator Symposium, San Diego, CA, June 26-28, 1990 (with T.G. Engel, M. Baker and L.L. Hatfield).
Abstract:  Not Available
+ The Influence of Magnetic Fields on Dielectric Surface Flashover
  R. Korzekwa, M. Lehr, H. Krompholz, M. Kristiansen, "The Influence of Magnetic Fields on Dielectric Surface Flashover", Proc. of 1990 Nineteenth Power Modulator Symposium, San Diego, Ca, June 26-28, 1990, pg. 277
Abstract:  Not Available
+ The Influence of Magnetic Fields on Dielectric Surface Flashover
  H. Krompholz, R. Korzekwa, M. Lehr, M. Kristiansen, "The Influence of Magnetic Fields on Dielectric Surface Flashover", Proc. 1990 Conference on Electrical Insulation and Dielectric Phenomena, Pocono Manor, PA, Oct. 28 - Nov. 1, 1990, p. 451
Abstract:  Not Available
+ Utilization of a Thermal Model to Predict Electrode Erosion Parameters of Engineering Importance
  "Utilization of a Thermal Model to Predict Electrode Erosion Parameters of Engineering Importance", Proc. 19th Power Modulator Symposium, San Diego, CA, June 26-28, 1990 (with A.L. Donaldson).
Abstract:  Not Available
Publication Year:  1989
+ A Single Gap Transformer Coupled L-C Generator with Resonant Frequency Compensa­tion
  "A Single Gap Transformer Coupled L-C Generator with Resonant Frequency Compensa­tion", 7th Pulsed Power Conference, Monterey, CA, June 12-14, 1989 (with B. Meyer, A. Watson, and G. Engel).
Abstract:  Not Available
+ An Assessment of Erosion Resistant Cathode Materials with Potential Application in High Power Electric Propulsion Devices
  "An Assessment of Erosion Resistant Cathode Materials with Potential Application in High Power Electric Propulsion Devices", AIAA ASME 25th Joint Propulsion Conference, Mon­terey, CA, July 10-14, 1989 (with A. Donaldson).
Abstract:  Not Available
+ Arcjet Cathode Erosion Studies
  "Arcjet Cathode Erosion Studies", AIAA/ASME 25th Joint Propulsion Conference, Mon­terey, CA, July 10-14, 1989 (with E. O'Hair, A. Donaldson, L. Hatfield, S. Harris, and S. Gardner).
Abstract:  Not Available
+ Electrode Erosion as a Function of Electrode Material in High Current, High Energy Transient Arcs
  "Electrode Erosion as a Function of Electrode Material in High Current, High Energy Transient Arcs", 7th Pulsed Power Conference, Monterey, CA, June 12­14, 1989 (with A.L. Donaldson).
Abstract:  Not Available
+ High Performance Insulator Materials for High Current Switching Applications
  "High Performance Insulator Materials for High Current Switching Applications", 7th Pulsed Power Conference, Monterey, CA, June 12-14, 1989 (with T.G. Engel, B.D. Smith, J.N. Marx, and R.D. Stevenson).
Abstract:  Not Available
+ Inhibiting Surface Flashover with Magnetic Field
  R. Korzekwa, M. Lehr, H. Krompholz, M. Kristiansen, "Inhibiting Surface Flashover with Magnetic Fields", IECEC '89 (24th Intersociety Energy Conversion Conference-"International Forum on Energy Engineering", August 6-11, 1989, Washington, D.C.)
Abstract:  Not Available
+ Inhibiting Surface Flashover with Magnetic Fields
  M. Lehr, R. Korzekwa, H. Krompholz, M. Kristiansen, "Inhibiting Surface Flashover with Magnetic Fields", Proc. of the 6th International Symposium on High Voltage Engineering, New Orleans, La, Aug. 1989, Vol. 3, paper 48.09
Abstract:  Not Available
+ Inhibiting Surface Flashover with Magnetic Insulation
  M. Lehr, R. Korzekwa, H. Krompholz, M. Kristiansen, "Inhibiting Surface Flashover with Magnetic Insulation", Proc. of the 7th IEEE Pulsed Power Conference, Monterey, Ca, June 1989, p. 812
Abstract:  Not Available
+ Inhibition of Dielectric Surface Flashover with Magnetic Fields for Space Conditions
  M. Lehr, R. Korzekwa, H. Krompholz, M. Kristiansen, "Inhibition of Dielectric Surface Flashover with Magnetic Fields for Space Conditions", Proc. of the 19th International Conference on Phenomena in Ionized Gases, Belgrade, Yugoslavia, July 1989, p. 86
Abstract:  Not Available
+ Optical Study of the Effects of Anode Geometry on the Performance of an Ignitron
  J.E. Burke, D.L. Loree, M. Giesselmann, and M. Kristiansen, "Optical Study of the Effects of Anode Geometry on the Performance of an Ignitron", Proceedings of the 7th IEEE Pulsed Power Conference, Monterey, California, June 11-14, 1989.
Abstract:  Not Available
+ Preliminary Interferometric Investigations of a Demountable Ignitron
  D.L. Loree, J.E. Burke, M. Giesselmann, and M. Kristiansen, "Preliminary Interferometric Investigations of a Demountable Ignitron", Proceedings of the 7th IEEE Pulsed Power Conference, Monterey, California, June 11-14, 1989.
Abstract:  Not Available
+ Preliminary Interferometric Investigations of a Demountable Ignitron
  "Preliminary Interferometric Investigations of a Demountable Ignitron", 7th Pulsed Power Conference, Monterrey, CA, June 12-14, 1989 (with D.L. Loree, J.E. Burke, and M. Kristiansen).
Abstract:  Not Available
Publication Year:  1988
+ Axial Magnetic Field Effects on Redesigned Ignitrons Utilizing Glass Walls and Cylindrical Dielectric Inserts
  D. Adkins-Loree, M. Giesselmann, and M. Kristiansen, "Axial Magnetic Field Effects on Redesigned Ignitrons Utilizing Glass Walls and Cylindrical Dielectric Inserts", Proceedings of the 18th Power Modulator Symposium, June 20-22, 1988, Hyatt Regency, Hilton Head Island, South Carolina, p. 241...246.
Abstract:  Not Available
+ Dielectric strength of High Power Ignitrons in Axial Magnetic Fields
  D. Adkins-Loree, M. Giesselmann and M. Kristiansen, "Dielectric strength of High Power Ignitrons in Axial Magnetic Fields", Proceedings of the 1988 IEEE International Symposium on Electrical Insulation and Dielectric Phenomena, CEIDP, October 1988, Ottawa, Canada, p. 72...77.
Abstract:  Not Available
+ Magnetic Insulation for Dielectric Surfaces
  R. Korzekwa, M. Lehr, H. Krompholz, M. Kristiansen, "Magnetic Insulation for Dielectric Surfaces", Beams '88, 7th Int. Conference on High Power Particle Beams, Karlsruhe, FRG, July 1988, vol. 2, p. 1061
Abstract:  Not Available
+ Magnetic Insulation for Space Environment
  H. Krompholz, R. Korzekwa, M. Lehr, M. Kristiansen, "Magnetic Insulation for Space Environment" SPSE conference on Space Power and Power Conditioning, Los Angeles, Ca, January 1988, pg. 341
Abstract:  Not Available
+ Magnetic Insulation of Dielectric Surfaces for Space Environment
  R. Korzekwa, M. Lehr, H. Krompholz, M. Kristiansen, "Magnetic Insulation of Dielectric Surfaces for Space Environment", 1988 IEEE International Symposium on Electrical Insulation, Boston, Ma., June 1988, p. 50
Abstract:  Not Available
+ Methods of Increasing the Surface Flashover Potential in Vacuum
  L.L. Hatfield, G.R. Leiker, E.R Boerwinkle, H. Krompholz, R. Korzekwa, M. Lehr, M. Kristiansen, "Methods of Increasing the Surface Flashover Potential in Vacuum", 13th Symposium on Discharges and Electrical Insulation in Vacuum, Paris, France, 1988, vol. 1, p. 241 (invited)
Abstract:  Not Available
+ New Results on a Coating which Increases the Surface Flashover Potential
  "New Results on a Coating which Increases the Surface Flashover Potential", 13th Symp. on Discharges and Elec. Insulation in Vacuum, Paris, France, June, 1988 (with L.L. Hatfield, G.R. Leiker, and E.R. Boerwinkle).
Abstract:  Not Available
+ Performance of In-Situ Copper Alloys as Electrodes in High Current, High Energy Switches
  "Performance of In-Situ Copper Alloys as Electrodes in High Current, High Energy Switches," SPIE O-E/Laser Conf., IST Section (Space Power and Power Conditioning), Los Angeles, CA, Jan. 1988 (with A.L. Donaldson and F.M. Lehr).
Abstract:  Not Available
+ State-of-the-Art Insulator and Electrode Materials for Use in High Current, High Energy Switching
  "State-of-the-Art Insulator and Electrode Materials for Use in High Current, High Energy Switching", Proc. 4th Symposium on Electromagnetic Launch Tech­nology, Austin, TX, April 1988 (with A.L. Donaldson and T.G. Engel).
Abstract:  Not Available
+ Surface Breakdown of Pre-Stressed Insulators
  "Surface Breakdown of Pre-Stressed Insulators," SPIE O-E/Laser Conf., IST Section (Space Power and Power Conditioning), Los Angeles, CA, Jan. 1988 (with L.L. Hatfield, V.K. Agarwal, and E.R. Menzel).
Abstract:  Not Available
+ The Effect of Repetition Rate on Electrode Material Performance in High Current Switches
  "The Effect of Repetition Rate on Electrode Material Performance in High Current Switches," SPIE O-E/Laser Conf., IST Section (Space Power and Power Conditioning), Los Angeles, CA, Jan. 1988 (with A.L. Donaldson and B.D. Smith).
Abstract:  Not Available
+ The Effects of Axial Magnetic Fields on High Current, High Coulomb Ignitrons
  D.L. Adkins-Loree, M. Giesselmann, M. Kristiansen, "The Effects of Axial Magnetic Fields on High Current, High Coulomb Ignitrons", Fall Meeting of AAPT, APS and SPS, November 4-5, 1988, Lubbock, Texas.
Abstract:  Not Available
+ The Performance of New, Redesigned Ignitron Tubes in Axial Magnetic Fields
  D. Adkins, M. Giesselmann, and M. Kristiansen, "The Performance of New, Redesigned Ignitron Tubes in Axial Magnetic Fields", 4th Symposium on Electromagnetic Launch Technology", April 19-21, 1988, Austin, Texas.
Abstract:  Not Available
Publication Year:  1987
+ Coating Properties which Enhance the Vacuum Surface Flashover Potential of Insulators
  "Coating Properties which Enhance the Vacuum Surface Flashover Potential of Insulators," Proc. 6th IEEE Pulsed Power Conf., June 29-July 1, 1987, Arlington, VA (with G.R. Leiker, L.L. Hatfield, C. Colmenares, W.W.Hofer, and M.S. DiCapua).
Abstract:  Not Available
+ Design and Analysis of Multi-Factor Reliability Experiments for Pulsed Power Devices
  "Design and Analysis of Multi-Factor Reliability Experiments for Pulsed Power Devices," Proc. the 6th IEEE Pulsed Power Conf., June 29-July 1, 1987, Arlington, VA (with W.J. Kolarik, J.M. Davenport, and K. McCoun).
Abstract:  Not Available
+ Electrode and Insulator Materials Performance in High Energy, High Current Switching
  "Electrode and Insulator Materials Performance in High Energy, High Current Switching", Proc. Society for the Advancement of Material and Process Engineering, Oct. 13-15, 1987, Crystal City, VA (with T. Engel and A. Donaldson).
Abstract:  Not Available
+ Electrode Erosion and Insulator Damage from Moving Arc Discharge
  "Electrode Erosion and Insulator Damage from Moving Arc Discharge," Proc. 5th International Symposium on High Voltage Engineering, Braunschweig, FRG, Aug. 24-28, 1987 (with G. Engel and F.M. Lehr).
Abstract:  Not Available
+ Methane-Attacher Mixtures in an Electron Beam Controlled Diffuse Discharge Opening Switch
  "Methane-Attacher Mixtures in an Electron Beam Controlled Diffuse Discharge Opening Switch," Proc. 6th IEEE Pulsed Power Conf., June 29-July 1, 1987, Arlington, VA (with G. Schaefer and R.A. Korzekwa).
Abstract:  Not Available
+ Moving Arc Damage to Insulator Materials
  "Moving Arc Damage to Insulator Materials, " Proc. 6th IEEE Pulsed Power Conf., June 29-July 1, 1987, Arlington, VA (with G. Engel).
Abstract:  Not Available
+ Penning Ionization Ternary Gas Mixtures for Diffuse Discharge Opening Switches
  "Penning Ionization Ternary Gas Mixtures for Diffuse Discharge Opening Switches", Proc. Fifth International Symposium on Gaseous Dielectrics, Knoxville, TN, May 1987 (with G. Schaefer, K.H. Schoenbach, and R.A. Korzekwa).
Abstract:  Not Available
+ State-of-the-Art Materials for High Current Contacts
  "State-of-the-Art Materials for High Current Contacts," Proc. 1987 International Current Collector Conference, UT at Austin, Nov. 1987 (with A.L. Donaldson and F.M. Lehr).
Abstract:  Not Available
+ The Influence of Arc Motion on Electrode Erosion in High Current, High Energy Switches
  "The Influence of Arc Motion on Electrode Erosion in High Current, High Energy Switches," Proc. the 6th IEEE Pulsed Power Conf., June 29-July 1, 1987, Arlington, VA (with F.M. Lehr, B.D. Smith, A.L. Donaldson).
Abstract:  Not Available
+ The Influence of Nitrogen on Argon Based Gas Mixtures for an Electron Beam Controlled Diffuse Discharge
  "The Influence of Nitrogen on Argon Based Gas Mixtures for an Electron Beam Controlled Diffuse Discharge", Proc. 18th ICPIG, Swansea, UK, July 1987 (with R.A. Korzekwa, G. Schaefer, and K.H. Schoenbach).
Abstract:  Not Available
Publication Year:  1986
+ A Gap Distance Threshold in Electrode Erosion in High Current, High Energy Spark Gaps
  "A Gap Distance Threshold in Electrode Erosion in High Current, High Energy Spark Gaps," Proc. 17th Power Mod. Symp., Seattle, WA, June 1986 (with A.L. Donaldson, D. Garcia, and A. Watson).
Abstract:  Not Available
+ A Treatment Which Inhibits Surface Flashover in Vacuum
  "A Treatment Which Inhibits Surface Flashover in Vacuum," Proc. XIIth Int. Symp. Discharges and Electrical Insulation in Vacuum," Israel, Sept. 1986 (with L.L. Hatfield, G.R. Leiker, C. Colmenares, W.W. Hoefer, and M.S. DiCapua).
Abstract:  Not Available
+ Breakdown of Insulators in the Space Environmen
  "Breakdown of Insulators in the Space Environment," Proc. 2nd Int. Conf. Conduction and Breakdown in Solid Dielectrics," Erlangen, FRG, July 7-10, 1986 (with V.K. Agarwal and L.L. Hatfield).
Abstract:  Not Available
+ Electrode Erosion and Insulator Damage from Moving Arc Discharges
  "Electrode Erosion and Insulator Damage from Moving Arc Discharges", Proc. of the First Meeting of the Non-Nuclear Space Power Consortium at Auburn Univ., Dec. 1986 (with F.M. Lehr, and T.G. Engel).
Abstract:  Not Available
+ Electrode Erosion in High Current, High Energy Transient Arcs
  "Electrode Erosion in High Current, High Energy Transient Arcs," Proc. 3rd Symp. Electromagnetic Launch Technology, Austin, TX, Apr. 1986 (with A.L. Donaldson, A. Watson, K. Zinsmeyer, E. Kristiansen, and R. Dethlefsen).
Abstract:  Not Available
+ Electrode Erosion Resulting from High Current Transient Arcing
  "Electrode Erosion Resulting from High Current Transient Arcing," Proc. of the First Meeting of the Non-Nuclear Space Power Consortium at Auburn Univ., Dec. 1986 (with A.L. Donaldson).
Abstract:  Not Available
+ Experimental Design in Life Cycle Life Testing
  "Experimental Design in Life Cycle Life Testing," 1986 High Voltage Workshop, Fort Monmouth, NJ, Oct. 1986 (with W.J. Kolarik, J.M. Davenport, and K. McCoun).
Abstract:  Not Available
+ Insulator and Electrode Damage Resulting from High Current (500 kA) Pulses
  "Insulator and Electrode Damage Resulting from High Current (500 kA) Pulses," 4th Int. Conf. Megagauss Magnetic Field Generation and Related Topics, Santa Fe, NM, July 1986 (with P. Ranon, A.L. Donaldson and A. Watson).
Abstract:  Not Available
+ Insulator Damage from a Moving Arc in a Surface Discharge Switch
  "Insulator Damage from a Moving Arc in a Surface Discharge Switch," CEIDP, Wilmington, DE, Nov. 1986 (with P.M. Ranon, A. Watson, T.G. Engel and L.L. Hatfield).
Abstract:  Not Available
+ Insulator Damage in High Current Discharges
  "Insulator Damage in High Current Discharges," Proc. 3rd Symp. Electromagnetic Launch Technology, Austin, TX, Apr. 1986 (with P.M. Ranon, M. Lehr and L.L. Hatfield).
Abstract:  Not Available
+ Interaction of Discharge and Circuit in an Electron-Beam Controlled Diffuse Discharge Opening Switch
  "Interaction of Discharge and Circuit in an Electron-Beam Controlled Diffuse Discharge Opening Switch," Proc. BEAMS '86, Kobe, Japan, June 1986 (with G. Schaefer, K.H. Schoenbach, B.E. Strickland, R.A. Korzekwa and K.R. Rathbun).
Abstract:  Not Available
+ Mechanism of Electrode Surface Damage and Material Removal in High Current Discharges
  "Mechanism of Electrode Surface Damage and Material Removal in High Current Discharges," Proc. 3rd Symp. Electromagnetic Launch Technology, Austin, TX, Apr. 1986 (with A. Watson, A.L. Donaldson and K. Ikuta).
Abstract:  Not Available
+ Negative Differential Conductivity in an Electron Beam Controlled Diffuse Discharge for Switching Applications
  "Negative Differential Conductivity in an Electron Beam Controlled Diffuse Discharge for Switching Applications," Proc. Int. Conf. Plasma Sci. and Technol., Beijing, China, June 1986 (with G. Schaefer, K.H. Schoenbach, B.E. Strickland and R.A. Korzekwa).
Abstract:  Not Available
+ Optimization of Gas Mixtures for Electron-Beam Controlled Diffuse Discharge Opening Switches
  "Optimization of Gas Mixtures for Electron-Beam Controlled Diffuse Discharge Opening Switches," Proc. 17th Power Mod. Symp., Seattle, WA, June 1986 (with G. Schaefer, K.H. Schoenbach, and R.A. Korzekwa).
Abstract:  Not Available
+ Overview of Applications and Needs
  "Overview of Applications and Needs," and "Ranking of Diagnostic Techniques," Proc. NATO Advanced Study Inst. on Fast Electrical and Optical Measurements," M. Nijhoff, Netherlands, 1986 (with A.K. Hyder and M.F. Rose).
Abstract:  Not Available
+ Reliability Assurance in Electromagnetic Launch Technology
  "Reliability Assurance in Electromagnetic Launch Technology, Proc. 3rd Symp. Electromagnetic Launch Technology, Austin, TX, Apr. 1986 (with W.J. Kolarik and T.L. Landers).
Abstract:  Not Available
+ Selection Criteria and Accelerated Aging of Insulators for Space Applications
  "Selection Criteria and Accelerated Aging of Insulators for Space Applications," Proc. of the First Meeting of the Non-Nuclear Space Power Consortium at Auburn Univ., Dec. 1986 (with L.L. Hatfield V.K. Agarwal, W.G. Linzey, and J. Culhane).
Abstract:  Not Available
Publication Year:  1985
+ An e-beam controlled diffuse discharge switch
  K. Schoenbach, G. Schaefer, M. Kristiansen, H. Krompholz, D. Skaggs, E. Strickland, "An e-beam controlled diffuse discharge switch", Proc. 5th IEEE Pulsed Power Conf., Arlington, VA, USA, 1985, p. 640
Abstract:  Not Available
+ An Electron-beam Controlled Diffuse Discharge Switch
  G. Schaefer, K. Schoenbach, M. Kristiansen, H. Krompholz, "An Electron-beam Controlled Diffuse Discharge Switch", Proc. XVII International Conference on Phenomena in Ionized Gases, Budapest, Hungary, 1985, p. 626
Abstract:  Not Available
+ Analysis of Electrode Surface Damage in High Energy Spark Gaps
  A.L. Donaldson, M. Kristiansen, H. Krompholz, M. Hagler, L. Hatfield, G. Leiker, P. Predecki, G. Jackson, "Analysis of Electrode Surface Damage in High Energy Spark Gaps", Proc. 5th IEEE Pulsed Power Conf., Arlington, VA, USA, 1985, p. 457
Abstract:  Not Available
+ Arc Current, Voltage, and Resistance in a High Energy, Gas Filled Spark Gap
  B. Maas, H. Krompholz, M. Kristiansen, M. Hagler, "Arc Current, Voltage, and Resistance in a High Energy, Gas Filled Spark Gap", Proc. 5th IEEE Pulsed Power Conference, Arlington, VA, USA, 1985, p. 99
Abstract:  Not Available
+ Electromagnetic Mass Drivers
  "Electromagnetic Mass Drivers," Scientific Bull., Office of Naval Research Far East, Dept. of the Air Force Office of Scientific Research Far East, Jan.-Mar., vol. 10, no. 1, 1985 (with F. Rose).
Abstract:  Not Available
+ Experiment to Investigate Current Drive by Fast Alfven Waves in a Small Tokamak
  "Experiment to Investigate Current Drive by Fast Alfven Waves in a Small Tokamak," Proc. 6th AIP Topical Conf. Radio Freq. Plasma Heating, No. 129, Callaway Gardens, GA, 1985 (with J. Gahl, O. Ishihara, K. Wong and M. Hagler).
Abstract:  Not Available
+ High Current Surface Discharge Switch
  P.M. Ranon, H. Krompholz, M. Kristiansen, L.L. Hatfield, "High Current Surface Discharge Switch", Proc. 5th IEEE Pulsed Power Conf., Arlington, VA, USA, 1985, p. 276
Abstract:  Not Available
+ Increased Flashover Potential of Polymers
  "Increased Flashover Potential of Polymers," Proc. 5th IEEE Pulsed Power Conf., Arlington, VA, June 1985 (with L.L. Hatfield and G. Leiker).
Abstract:  Not Available
+ Inertial Confinement Fusion Research in Japan
  "Inertial Confinement Fusion Research in Japan," Scientific Bulletin, Dept. of the Navy Office of Naval Research Far East and Dept. of the Air Force Office of Scientific Research Far East 10(2), 171, 1985 (with M. Frank Rose).
Abstract:  Not Available
+ Pulsed Power Research in Japan
  "Pulsed Power Research in Japan," Scientific Bulletin, Dept. of the Navy Office of Naval Research Far East and Dept. of the Air Force Office of Scien­tific Research Far East 10(2), 169, 1985 (with M. Frank Rose).
Abstract:  Not Available
+ Striations in High Pressure Diffuse Discharges
  "Striations in High Pressure Diffuse Discharges," Proc. NATO Advanced Study Institute on Radioactive Processes in Discharge Plasma, Pitlochry, Scotland, June 23-25, 1985 (with K.H. Schoenbach, G. Schaefer, E. Strickland, and O. Ishihara).
Abstract:  Not Available
Publication Year:  1984
+ An E-Beam Controlled Diffuse Discharge Switch
  K. Schoenbach, G. Schaefer, M. Kristiansen, H. Krompholz, H. Harjes, D. Skaggs, "An E-Beam Controlled Diffuse Discharge Switch", 16th IEEE Power Modulator Symposium, Arlington, Virginia, USA 1984, p. 152
Abstract:  Not Available
+ Antenna System Without Matching Circuitry for Unidirectional Propagation of Alfven Waves
  "Antenna System Without Matching Circuitry for Unidirectional Propagation of Alfven Waves," Proc. 3rd All Union Conf. Engrg. Problems of Fusion Reactors, Leningrad, USSR, June 20-22, 1984 (with H. Akiyama, J. Gahl, K. Rathbun and M.O. Hagler).
Abstract:  Not Available
+ Investigations of E-Beam Controlled Diffuse Discharge
  K. Schoenbach, G. Schaefer, M. Kristiansen, H. Krompholz, H. Harjes, D. Skaggs, "Investigations of E-Beam Controlled Diffuse Discharges", 4th Int. Symp. on Gaseous Dielectrics, Knoxville, TN, USA, 1984
Abstract:  Not Available
+ Recovery Measurements in a Spark Gap
  C. Yeh, H. Krompholz, M. Hagler, M. Kristiansen, "Recovery Measurements in a Spark Gap", 16th IEEE Power Modulator Symposium, Arlington, Virginia, USA 1984, p. 64
Abstract:  Not Available
Publication Year:  1983
+ A Multi-Spark Preionization Source for Diffuse Discharges Containing Attachers
  "A Multi-Spark Preionization Source for Diffuse Discharges Containing Attachers", Proc. 4th IEEE Pulsed Power Conf., Albuquerque, NM, June 1983 (with R. Cooper, G. Hutcheson, G. Schaefer, K.H. Schoenbach, and A.H. Guenther).
Abstract:  Not Available
+ An Introduction to Gas Filled Spark Gaps
  "An Introduction to Gas Filled Spark Gaps," Proc. ARO Workshop on Repetitive Spark Gap Operation, Tamarron, CO, Jan. 1983. DTIC No. AD-A132688.
Abstract:  Not Available
+ E-Beam Triode for Multiple Submicrosecond Pulse Operation
  "E-Beam Triode for Multiple Submicrosecond Pulse Operation," Proc. 4th IEEE Pulsed Power Conf., Albuquerque, NM, June 1983 (with H. Harjes, K. Schoen­bach, G. Schaefer and H. Krompholz).
Abstract:  Not Available
+ E-Beam Triode for Multiple Submicrosecond Pulse Operation
  H. Harjes, K. Schoenbach, G. Schaefer, H. Krompholz, M. Kristiansen, G. Leiker, L. Hatfield, "E-Beam Triode for Multiple Submicrosecond Pulse Operation", 4th IEEE Pulsed Power Conference, Albuquerque, New Mexico, USA, 1983, p. 474
Abstract:  Not Available
+ Electrode Erosion in a High Energy Spark Gap
  "Electrode Erosion in a High Energy Spark Gap," Proc. 4th IEEE Pulsed Power Conf., Albuquerque, NM, June 1983 (with A.L. Donaldson, M. Hagler, G. Jack­son, L. Hatfield and J. Marx).
Abstract:  Not Available
+ Nanosecond Current Probe for High Voltage Experiments
  "Nanosecond Current Probe for High Voltage Experiments," Proc. 4th IEEE Pulsed Power Conf., Albuquerque, NM, June 1983 (with H. Harjes, J. Doggett, J. Gahl, K. Zinsmeyer, H. Krompholz, K. Schoenbach and G. Schaefer).
Abstract:  Not Available
+ Nanosecond Current Probe for High Voltage Experiments
  H. Harjes, J. Doggett, J. Gahl, K. Zinsmeyer, H. Krompholz, K. Schoenbach, G. Schaefer, M. Kristiansen, "Nanosecond Current Probe for High Voltage Experiments", 4th IEEE Pulsed Power Conference, Albuquerque, New Mexico, USA 1983, p. 396
Abstract:  Not Available
+ Pulsed Flashover of Solid Dielectrics in Gases
  "Pulsed Flashover of Solid Dielectrics in Gases," Proc. 4th IEEE Pulsed Power Conf., Albuquerque, NM, June 1983 (with G. Jackson, L. Hatfield, G. Leiker and J. Marx).
Abstract:  Not Available
+ Pulsed Power Education
  "Pulsed Power Education," Proc. 4th IEEE Pulsed Power Conf., Albuquerque, NM, June 1983 (with A. Guenther, J. Ungvarsky, T. Skvarenina, A. Hyder, and H. Pugh).
Abstract:  Not Available
+ Pulsed Power Technology and Diffuse Discharges
  "Pulsed Power Technology and Diffuse Discharges," Proc. US-FRG Joint Seminar on Externally Contr. Diffuse Discharges," Bad Honnef, FRG, Aug. 1983 (with M.F. Rose).
Abstract:  Not Available
+ Repetitive Spark Gap Operation--A Review of the Tamarron Workshop
  "Repetitive Spark Gap Operation--A Review of the Tamarron Workshop," Proc. 4th IEEE Pulsed Power Conf., Albuquerque, NM, June 1983 (with M.O. Hagler).
Abstract:  Not Available
+ Solid State Pulsed Power Switching--A Review of the Tamarron Workshop
  "Solid State Pulsed Power Switching--A Review of the Tamarron Workshop," Proc. 4th IEEE Pulsed Power Conf., Albuquerque, NM, June 1983 (with W.M. Portnoy).
Abstract:  Not Available
+ Summary of the Capabilities of Repetitive Spark Gap Switches
  "Summary of the Capabilities of Repetitive Spark Gap Switches," Proc. ARO Workshop on Repetitive Spark Gap Operation, Tamarron, CO, Jan. 1983 (with I. Smith, T. Burkes, A. Guenther and G. Lauer). DTIC No. AD-A132688.
Abstract:  Not Available
+ Surface Charging of Insulators in Surface Discharge Switches
  "Surface Charging of Insulators in Surface Discharge Switches," Proc. Conf. Electrical Insulation and Dielectric Phenomena, Buckhill Falls, PA, Oct. 1983 (with R. Curry, L. Hatfield, V. Agarwal and G. Jackson).
Abstract:  Not Available
+ Surface Studies of Dielectric Materials used in Spark Gaps
  "Surface Studies of Dielectric Materials used in Spark Gaps," Proc. 4th IEEE Pulsed Power Conf., Albuquerque, NM, June 1983 (with G. Jackson, L. Hatfield, M. Hagler, J. Marx, A. Donaldson, G. Leiker, R. Curry, R. Ness, L. Gordon and D. Johnson).
Abstract:  Not Available
+ Surface Studies of Electrodes used in Spark Gaps
  "Surface Studies of Electrodes used in Spark Gaps," Proc. 4th IEEE Pulsed Power Conf., Albuquerque, NM, June 1983 (with G. Jackson, G. Leiker, L. Hatfield, M. Hagler, A. Donaldson, R. Ness and J. Marx).
Abstract:  Not Available
+ Triggering of Surface Discharge Switches
  "Triggering of Surface Discharge Switches," Proc. 4th IEEE Pulsed Power Conf., Albuquerque, NM, June 1983 (with R. Curry, D. Johnson, L. Hatfield, and A.H. Guenther).
Abstract:  Not Available
+ Voltage Recovery Measurements in a High Energy Spark Gap
  "Voltage Recovery Measurements in a High Energy Spark Gap," Proc. 4th IEEE Pulsed Power Conf., Albuquerque, NM, June 1983 (with C. Yeh and M. Hagler).
Abstract:  Not Available
Publication Year:  1982
+ Electrode Erosion in High Power Spark Gaps
  "Electrode Erosion in High Power Spark Gaps," Proc. 15th Power Modulator Symp., Baltimore, MD, June 1982 (with A. Donaldson, R. Ness and M.O. Hagler).
Abstract:  Not Available
+ Multichannel Surface Discharge Switch
  "Multichannel Surface Discharge Switch," Proc. Conf. Elec. Insulation and Dielectric Phenomena, Amherst, MA, Oct. 1982 (with D. Johnson and L.L. Hatfield).
Abstract:  Not Available
+ Optical Control of Diffuse Discharge Opening Switches
  "Optical Control of Diffuse Discharge Opening Switches," Proc. U.S. Army Workshop on Diffuse Discharge Opening Switches," Tamarron, CO, Jan. 1982 (with K.H. Schoenbach, G. Schaefer, L.L. Hatfield and A.H. Guenther) DTIC No. AD-A115883.
Abstract:  Not Available
+ Optical Control of Discharge Opening Switches
  "Optical Control of Discharge Opening Switches," Proc. US Army Workshop on Diffuse Opening Switches, Tamarron, CO, Apr. 1982 (with K.H. Schoenbach, G. Schaefer, A.H. Guenther and L.L. Hatfield). DTIC No. AD-A115883.
Abstract:  Not Available
+ Pulse Flashover of Solid Dielectrics in Vacuum
  "Pulse Flashover of Solid Dielectrics in Vacuum," Proc. 10th Int. Symp. Discharges and Elec. Insulation in Vacuum, Columbia, SC, Oct. 1982 (with D. Johnson, L.L. Hatfield, J. Marx and A. Bowling).
Abstract:  Not Available
Publication Year:  1981
+ Diffuse Discharge Opening Switches
  "Diffuse Discharge Opening Switches," Proc. NATO Advanced Study Institute on Breakdown and Discharges in Gases, Les Arcs, France, 1981 (with K.H. Schoen­bach, G. Schaefer, L.L. Hatfield and A.H. Guenther). NATO ASI Series B: Physics 89B, Plenum Press (1983), p. 415.
Abstract:  Not Available
+ Exploratory Concepts of Opening Switches
  "Exploratory Concepts of Opening Switches", Proc. US Army Workshop on Repetitive Opening Switches, 65-105, Tamarron, CO, Jan. 1981 (with K.H. Schoen­bach, A.H. Guenther and E.E. Kunhardt).
Abstract:  Not Available
+ Investigations of a 60 KV, 5 cm Spark Gap for Several Electrode, Insulator and Gas Types
  "Investigations of a 60 KV, 5 cm Spark Gap for Several Electrode, Insulator and Gas Types," Proc. 3rd IEEE Int. Pulsed Power Conf., Albuquerque, NM, June 1981 (with L.B. Gordon, M.O. Hagler and H.C. Kirbie).
Abstract:  Not Available
+ Magnetic Probe Measurements of Toroidal Eigenmodes in the Texas Tech Tokamak
  "Magnetic Probe Measurements of Toroidal Eigenmodes in the Texas Tech Tokamak," Proc. 4th Topical Conf. RF Plasma Heating, Austin, TX, Feb. 1981 (with P.D. Coleman, B.D. Blackwell and M.O. Hagler).
Abstract:  Not Available
+ Modular Instructional Material in Pulsed Power Technology
  "Modular Instructional Material in Pulsed Power Technology," Proc. 3rd IEEE Int. Pulsed Power Conf., Albuquerque, NM, June 1981 (with A.H. Guenther, J. Ungvarsky, F. Brockhurst, R.D. Franklin, A.K. Hyder and R.L. Gullickson).
Abstract:  Not Available
+ Opening Switches
  "Opening Switches," Proc. 3rd IEEE Int. Pulsed Power Conf., Albuquerque, NM, June 1981 (with K.H. Schoenbach, G. Schaefer, E.E. Kunhardt and A.H. Guenther).
Abstract:  Not Available
+ Plasma Applications
  "Plasma Applications," Proc. NATO Advanced Study Institute: Electrical Breakdown and Discharge in Gases, Les Arcs, France, July 1981 (with A.H. Guenther). NATO ASI Series B: Physics 89B, Plenum Press (1983), p. 383.
Abstract:  Not Available
+ Probe Measurements of the Magnetic Field Structure of Toroidal Eigenmodes in the Texas Tech Tokamak
  "Probe Measurements of the Magnetic Field Structure of Toroidal Eigenmodes in the Texas Tech Tokamak," Proc. 2nd All-Union Conf. Engrg. Problems of Thermo­nuclear Reactors 2, 54, Leningrad, USSR, June 23-25, 1981 (with P.D. Coleman, B.D. Blackwell and M.O. Hagler).
Abstract:  Not Available
+ Pulsed Power Education at Texas Tech University
  "Pulsed Power Education at Texas Tech University," Proc. 3rd IEEE Int. Pulsed Power Conf., Albuquerque, NM, June 1981 (with E.E. Kunhardt).
Abstract:  Not Available
+ Space Charge Effects in a Laser-Fiber Optics Triggered Multichannel Spark Gap
  "Space Charge Effects in a Laser-Fiber Optics Triggered Multichannel Spark Gap," Proc. 3rd IEEE Int. Pulsed Power Conf., Albuquerque, NM, June 1981 (with H.C. Harjes, E.E. Kunhardt, and L.L. Hatfield).
Abstract:  Not Available
+ Surface Damage of Dielectrics in a Spark Gap
  "Surface Damage of Dielectrics in a Spark Gap," Proc. 3rd IEEE Int. Pulsed Power Conf., Albuquerque, NM, June 1981 (with G.L. Jackson, K.-C Yuan and L.L. Hatfield).
Abstract:  Not Available
Publication Year:  1980
+ Discharge Phenomena in Pulsed Power Applications
  "Discharge Phenomena in Pulsed Power Applications", Proc. NSF Workshop on Plasma Chemistry and Arc Technology, Univ. of Minnesota, Minneapolis-St. Paul, MN, 1980 (with A.H. Guenther and A. Garscadden).
Abstract:  Not Available
+ Investigations of Reed Switch Dynamics When Switching Heavy Loads
  "Investigations of Reed Switch Dynamics When Switching Heavy Loads," Proc. 10th Int. Conf. Contact Phenomena, Bucharest, Hungary, Aug. 25-29, 1980 (with B. Miedzinski).
Abstract:  Not Available
+ Probe Measurements of the Magnetic Field Structure of Fast Wave Toroidal Eigenmodes
  "Probe Measurements of the Magnetic Field Structure of Fast Wave Toroidal Eigenmodes," Proc. Int. Symp. Heating in Toroidal Plasmas, Como, Italy, 1980 (with P.D. Coleman, B.D. Blackwell and M.O. Hagler).
Abstract:  Not Available
Publication Year:  1979
+ An Electron-Beam-Triggered Spark Gap
  "An Electron-Beam-Triggered Spark Gap," Proc. 2nd IEEE Int. Pulsed Power Conf., Lubbock, TX, June 12-14, 1979 (with L.L. Hatfield, H.C. Harjes, A.H. Guenther and K.H. Schoenbach).
Abstract:  Not Available
+ Applications of Electron Beams for Precise Switching of High Voltages
  "Applications of Electron Beams for Precise Switching of High Voltages," Proc. 3rd Int. Topical Conf. High Power Electron and Ion Beam Res. and Techn., Novosibirsk, USSR, July 3-6, 1979 (with M. Newton, K. McDonald, E.E. Kunhardt and A.H. Guenther).
Abstract:  Not Available
+ High Power Switch Capabilities
  "High Power Switch Capabilities," Proc. Switching and Pulse Compression Conf., Venice, Italy, 1979 (with H. Odem, T. Burkes, W. Portnoy, M. Hagler and J.P. Craig).
Abstract:  Not Available
+ Investigations of Fast Insulator Surface Flashover
  "Investigations of Fast Insulator Surface Flashover," Proc. 2nd IEEE Int. Pulsed Power Conf., Lubbock, TX, June 12-14, 1979 (with J.E. Thompson, J. Lin and K. Mikkelson).
Abstract:  Not Available
+ Investigations of Various Probe Sheath Materials in the Texas Tech Tokamak
  "Investigations of Various Probe Sheath Materials in the Texas Tech Tokamak," Proc. 8th Symp. Engrg. Problems of Fusion Res., San Francisco, CA, Nov. 1979 (with P.D. Coleman, B.D. Blackwell, S.R, Beckerich, C.K. Rothstein and M.O. Hagler).
Abstract:  Not Available
+ Simulation of Inductive and Electromagnetic Effects Associated with Single and Multichannel Triggered Spark Gaps
  "Simulation of Inductive and Electromagnetic Effects Associated with Single and Multichannel Triggered Spark Gaps," Proc. 2nd IEEE Int. Pulsed Power Conf., Lubbock, TX, June 12-14, 1979 (with S. Levinson, E.E. Kunhardt and A.H. Guenther).
Abstract:  Not Available
Publication Year:  1978
+ Description of the Texas Tech Tokamak
  "Description of the Texas Tech Tokamak," Proc. Small Toroidal Plasma Devices Users Mtg., 7, May 18, 1978, Rept. DOE-ET-78-G--05-5918 (with S.O. Knox, H.C. Kirbie, R.C. Cross and M.O. Hagler).
Abstract:  Not Available
+ High Power Switching Capabilities
  "High Power Switching Capabilities," 13th Pulsed Power Modulator Symp., SUNY/Buffalo, NY, June 20-22, 1978 (with T.R. Burkes, J.P. Craig, M.O. Hagler and W.M. Portnoy).
Abstract:  Not Available
Publication Year:  1977
+ An Experimental Arrangement for Laser Beat Heating of Plasma
  "An Experimental Arrangement for Laser Beat Heating of Plasma," Proc. 7th Symp. on Engrg. Problems of Fusion Research, 1615, Oct. 25-28, 1977 (with E.Y. Chu, R. Druce, L. Gordon, J. Jasper and M.O. Hagler).
Abstract:  Not Available
Publication Year:  1976
+ Laser Heating of Magnetized Plasma
  "Laser Heating of Magnetized Plasma," Proc. 1st Minicourse on Fusion, Austin, TX, May 26-28, 1976 (with M.O. Hagler).
Abstract:  Not Available
+ Switching Requirements for Fusion Reactors
  "Switching Requirements for Fusion Reactors," Proc. DoD Workshop on Pulsed Power, NSWC, White Oakes, Sept. 20-23, 1976.
Abstract:  Not Available
Publication Year:  1975
+ A Helical Antenna for Exciting Azimuthally Asymmetric Alfven Waves
  "A Helical Antenna for Exciting Azimuthally Asymmetric Alfven Waves", Proc. US-Australian Workshop on Plasma Waves, Australia, Feb. 13-18, 1975 (with S.O. Knox, F.J. Paoloni and M.O. Hagler).
Abstract:  Not Available
Publication Year:  1974
+ Carbon Dioxide Laser Interaction with Magnetized Plasma
  "Carbon Dioxide Laser Interaction with Magnetized Plasma," IEEE '74 Region VI Conf. Proc., Albuquerque, NM, 1974 (with G.M. Molen).
Abstract:  Not Available
+ Damping of the Fast Wave and Plasma Heating by an Unidentified Mechanism
  "Damping of the Fast Wave and Plasma Heating by an Unidentified Mechanism," Proc. 2nd Topical RF Plasma Heating, Texas Tech Univ., Lubbock, TX, June 20­22, 1974, D8 (with R. Dollinger, J. Bergstrom, M.O. Hagler and F.J. Paoloni).
Abstract:  Not Available
+ Experimental Investigations of a Helical Antenna for Exciting Alfven Waves
  "Experimental Investigations of a Helical Antenna for Exciting Alfven Waves," Proc. 2nd Topical Conf. RF Plasma Heating, Texas Tech Univ., Lubbock, TX, June 20-24, 1974, C2 (with S.O. Knox, F.J. Paoloni and M.O. Hagler).
Abstract:  Not Available
+ Simple, Solid Dielectric Start Switch
  "Simple, Solid Dielectric Start Switch," Proc. Int. Conf. Energy Storage, Compression and Switching, Torino, Italy, Nov. 5-7, 1974 (with W.C. Nunnally and M.O. Hagler). Published by Plenum Publishing Corp.
Abstract:  Not Available
Publication Year:  1973
+ Plasma Heating and Damping of the Fast Wave Near the Second Harmonic of the Ion Cyclotron Frequency
  "Plasma Heating and Damping of the Fast Wave Near the Second Harmonic of the Ion Cyclotron Frequency," Proc. 6th Eur. Conf. Contr. Fusion and Plasma Phys., Moscow, USSR, July 30 - Aug. 3, 1973 (with R. Dollinger, M.O. Hagler and J. Bergstrom).
Abstract:  Not Available
Publication Year:  1972
+ Enhanced Energy Transfer to a Cylindrical Plasma by an Alfven Wave
  "Enhanced Energy Transfer to a Cylindrical Plasma by an Alfven Wave," Proc. 1st Topical Conf. RF Plasma Heating, Texas Tech Univ., Lubbock, TX, July 6-8, 1972, A6 (with D.B. Lancaster and M.O. Hagler).
Abstract:  Not Available
+ Fast Plasma Heating for Thermonuclear Power (AFOSR-69-1757)
  "Fast Plasma Heating for Thermonuclear Power (AFOSR-69-1757)," Proc. AFOSR Contractors Meeting, Univ. Rochester, Rochester, NY, June 7-9, 1972 (with M.O. Hagler).
Abstract:  Not Available
+ Fast Wave Damping at the Second Harmonic of the Ion Cyclotron Frequency
  "Fast Wave Damping at the Second Harmonic of the Ion Cyclotron Frequency," Proc. 5th Eur. Conf. Contr. Fusion and Plasma Phys., Grenoble, France, Aug. 21-25, 1972, 117 (with J.E. Cato, C.N. Watson-Munro and M.O. Hagler).
Abstract:  Not Available
+ Fast Wave Propagation and Damping at the Second Harmonic of the Ion Cyclotron Frequency
  "Fast Wave Propagation and Damping at the Second Harmonic of the Ion Cyclotron Frequency," Proc. 1st Topical Conf. RF Plasma Heating, Texas Tech Univ., Lubbock, TX, July 6-8, 1972, B4 (with J.E. Cato, C.N. Watson-Munro and M.O. Hagler).
Abstract:  Not Available
Publication Year:  1971
+ Axial Magnetic Field Effects in a CO2 Laser Discharge
  "Axial Magnetic Field Effects in a CO2 Laser Discharge," Proc. 10th Int. Conf. Phenomena in Ionized Gases, Oxford, England, Sept. 14-17, 1971, p. 15 (with M.O. Hagler, G.M. Molen and L.G. Roseland).
Abstract:  Not Available
+ Current Practices and Trends in European Engineering Education
  "Current Practices and Trends in European Engineering Education," SWIEEECO Conf. Rec., Apr. 1971 (with M.O. Hagler).
Abstract:  Not Available
Publication Year:  1970
+ A Review of Fusion Reactor Design
  "A Review of Fusion Reactor Design," Proc. Frontiers Power Techn. Conf., Oklahoma State Univ., Stillwater, OK, Oct. 15-16, 1970 (with M.O. Hagler).
Abstract:  Not Available
+ Undergraduate Laser Experiments
  "Undergraduate Laser Experiments," SWIEEECO Conf. Rec. 53 (1970) (with G.M. Molen, C.R. Parten and M.O. Hagler).
Abstract:  Not Available
Publication Year:  1969
+ Investigations of the Macaluso-Corbino Effect in a 3.39 Micron He-Ne Laser
  "Investigations of the Macaluso-Corbino Effect in a 3.39 Micron He-Ne Laser," Proc. 9th Int. Ionization Conf., Bucharest, Rumania, 1969 (with M.O. Hagler and V.C. West).
Abstract:  Not Available
+ Laser Experiments for Undergraduate Electrical Engineering Students
  "Laser Experiments for Undergraduate Electrical Engineering Students," SWIEEECO Conf. Rec., Apr. 1969 (with L.N. Peckham and M.O. Hagler).
Abstract:  Not Available
+ Polarization Modulation Using the Macaluso-Corbino Effect
  "Polarization Modulation Using the Macaluso-Corbino Effect," SWIEEECO Conf. Rec. 7D1, Apr. 1969 (with V.C. West and M.O. Hagler).
Abstract:  Not Available
Publication Year:  1968
+ Controlled Thermonuclear Fusion--Some Recent Developments
  "Controlled Thermonuclear Fusion--Some Recent Developments," IEEE Reg. III Conf. Rec., Apr. 1968 (with M.O. Hagler).
Abstract:  Not Available
+ Current Investigations of High Power RF Heating of Magneto-plasma
  "Current Investigations of High Power RF Heating of Magneto-plasma," IEEE Reg. III Conf. Rec., Apr. 1968 (with J.E. Cato).
Abstract:  Not Available
+ Investigations of RF Energy Couplers for Resonant Plasma Heating
  "Investigations of RF Energy Couplers for Resonant Plasma Heating," SWIEEECO Conf. Rec., Apr. 1968 (with J.Hipp).
Abstract:  Not Available
+ Plasma Heating and Wave Propagation at Harmonics of the Ion Cyclotron Frequency
  "Plasma Heating and Wave Propagation at Harmonics of the Ion Cyclotron Frequency," Proc. European Conf. Controlled Fusion and Plasma Physics, Stock­holm, Aug. 1967; also Plasma Phys. 10, 460 (1968) (with A.A. Dougal).
Abstract:  Not Available
+ The Feasibility of Emergency Power Transmission with CO2 Lasers
  "The Feasibility of Emergency Power Transmission with CO2 Lasers," Proc. Frontiers of Power Techn. Conf., Stillwater, OK, Oct. 1968 (with M.O. Hagler).
Abstract:  Not Available
Publication Year:  1967
+ Plasma Heating and Wave Propagation at Harmonics of the Ion Cyclotron Frequency
  "Plasma Heating and Wave Propagation at Harmonics of the Ion Cyclotron Frequency," Proc. European Conf. Controlled Fusion and Plasma Physics, Stock­holm, Aug. 1967; also Plasma Phys. 10, 460 (1968) (with A.A. Dougal).
Abstract:  Not Available

Book

Publication Year:  1987
+ Advances in Pulsed Power Technology
  Advances in Pulsed Power Technology, Plenum Press, 1987 - (Series Editor with A. Guenther). a) Vol. I. "High Power Opening Switches", Volume Editor with A. Guenther and T. Martin (1987). b) Vol. 2. "Gas Discharge Closing Switches", Volume Editor G. Schaefer (1991). c) Vol. 3. "J.C. Martin on Pulsed Power", Volume Editor with A. Guenther and T. Martin (1996).
Abstract:  Not Available
Publication Year:  1980
+ An Introduction to Controlled Thermonuclear Fusion
  An Introduction to Controlled Thermonuclear Fusion, Lexington Press, 1977, Japanese and Russian Edition 1980; Chinese Edition, 1981 (with M.O. Hagler).
Abstract:  Not Available