M. Kristiansen

Bio: M. Kristiansen is an academic researcher from Texas Tech University. The author has contributed to research in topics: Pulse generator & Pulsed power. The author has an hindex of 29, co-authored 386 publications receiving 4022 citations. Previous affiliations of M. Kristiansen include University of Texas at Austin.

A review of short pulse generator technology

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.

J. C. Martin on pulsed power

Abstract: High Speed Pulsed Power Technology at Aldermaston M.J. Goodman. J.C. 'Charlie' Martin, C.B.E. Brief and Probably Not Very Accurate History of Pulsed Power at Atomic Weapons Research Establishment Aldermaston. Nanosecond Pulse Techniques. Hull Lecture Notes. Gas Breakdown. Liquid Breakdown. Solid Breakdown. Fast Pulse Vacuum Flashover. Switching. Beams. High Voltage Design Considerations. Index.

Gas discharge closing switches

Abstract: 1 General Switching Considerations.- 2 Electrical Breakdown In Gases In Electric Fields.- 3 Gas Filled Spark Gaps.- Section 3a Self Breakdown Gaps.- Section 3b Trigatron Spark Gaps.- Section 3c Field Distortion Three Electrode Gaps.- Section 3d Electron Beam Triggering of Gas Filled Spark Gaps.- Section 3e Laser Triggering of Gas Filled Spark Gaps.- 4 Vacuum Switches.- Section 4a Electrical Breakdown in Vacuum.- Section 4b Recovery of Vacuum Spark Gaps.- Section 4c Triggered Vacuum Switch Construction and Performance.- 5 Repetitive Operation and Lifetime Considerations for Spark Gaps.- Section 5a Repetitive Spark Gap Switches.- Section 5b Lifetime Considerations.- 6 Surface Discharge Switches.- 7 Thyratrons.- Section 7a Design Principles and Operation Characteristics.- Section 7b Hydrogen Thyratrons and Their Applications as Developed in the UK.- Section 7c Studies of Fundamental Processes in Thyratrons.- Section 7d Fundamental Limitations of Hydrogen Thyratron Discharges.- 8 Metal Vapor Switches.- Section 8a The Mercury-Pool-Cathode Ignitron.- Section 8b Liquid-Metal Plasma Valves.- 9 The Pseudospark Switch.- Section 9a The Pseudospark.- Section 9b The Triggered Pseudospark Discharge.- Section 9c The Back-Lighted Thyratron.- Section 9d High Power, High Current Pseudospark Switches.- Section 9e Pseudospark Switches for High Repetition Rates and Fast Current Risetimes.- Contributors.

The pulsed discharge arc resistance and its functional behavior

Abstract: A generalized comparison of several theoretical and empirical arc-resistance equations was conducted by normalizing the theoretical and experimental arc-resistance values at t=0.5 mu s (approximate time of maximum arc current). It was found that the arc-resistance equations considered could be grouped according to their functional form and were either of the inverse integral or inverse exponential form. The accuracies of both are discussed. At pressures approaching one atmosphere, it has been shown that the equations developed by I.V. Demenik et al. (1968), Kushner et al. (1985), Rompe and W. Weizel (1944), and A.E. Vlastos (1972) were equally accurate predictions of arc resistance for 0.1 mu s >

The role of outgassing in surface flashover under vacuum

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/sup -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.

Non-thermal plasmas in and in contact with liquids

Abstract: During the last two decades atmospheric (or high) pressure non-thermal plasmas in and in contact with liquids have received a lot of attention in view of their considerable environmental and medical applications. The simultaneous generation of intense UV radiation, shock waves and active radicals makes these discharges particularly suitable for decontamination, sterilization and purification purposes. This paper reviews the current status of research on atmospheric pressure non-thermal discharges in and in contact with liquids. The emphasis is on their generation mechanisms and their physical characteristics.

Plasma-liquid interactions: A review and roadmap

Abstract: Plasma–liquid interactions represent a growing interdisciplinary area of research involving plasma science, fluid dynamics, heat and mass transfer, photolysis, multiphase chemistry and aerosol science. This review provides an assessment of the state-of-the-art of this multidisciplinary area and identifies the key research challenges. The developments in diagnostics, modeling and further extensions of cross section and reaction rate databases that are necessary to address these challenges are discussed. The review focusses on non-equilibrium plasmas.

Intracellular effect of ultrashort electrical pulses.

Abstract: A simple electrical model for biological cells predicts an increasing probability for electric field interactions with cell substructures of prokaryotic and eukaryotic cells when the electric pulse duration is reduced into the sub-microsecond range. The validity of this hypothesis was verified experimentally by applying electrical pulses with electric field intensities of up to 5.3 MV/m to human eosinophils in vitro. When 3-5 pulses of 60 ns duration were applied to human eosinophils, intracellular granules were modified without permanent disruption of the plasma membrane. In spite of the extreme electrical power levels applied to the cells thermal effects could be neglected because of the ultrashort pulse duration. The intracellular effect extends conventional electroporation to cellular substructures and opens the potential for new applications in apoptosis induction, gene delivery to the nucleus, or altered cell functions, depending on the electrical pulse conditions.

Fast-wave heating of a two-component plasma

Abstract: The use of the compressional hydromagnetic mode (also called the magnetosonic or, simply, the fast wave) is examined in some detail with respect to the heating of a tritium plasma containing a few percent deuterium. Efficient absorption of wave energy by the deuteron component is found when ω = ωC (deuterons), with Qwave 100. Reasonable efficiencies are found also for electron heating, but coherence effects between transit-time and Landau damping for electrons reduce the total absorption for both processes to one-half of the transit-time power, calculated separately.The fusion output of a two-component neutral-injected plasma can be enhanced by selective heating of the injected deuterons. Also, selective deuteron absorption may be used for ion-tail creation by radiofrequency excitation alone, as an alternative to neutral injection. The dominant behaviour of the high-energy deuteron distribution function is found to be f(v) ~ exp[(3/2)∫vdv / ], where is the Chandrasekhar-Spitzer drag coefficient, and is the Kennel-Engelmann quasi-linear diffusion coefficient for wave-particle interaction at the deuteron cyclotron frequency. An analytic solution to the one-dimensional Fokker-Planck equation, with r.f.-induced diffusion, is developed, and using this solution together with Duane's fit to the D-T fusion cross-section, it is found that the nuclear-fusion power output from an r.f.-produced two-component plasma can significantly exceed the incremental (radiofrequency) power input.