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Over the past century, several models of spark discharge have been developed that approximate the effect of a spark channel in a circuit as a nonlinear resistance. In this article, we review the physical derivations of a set of spark models, and give analytical and numerical solutions to spark discharges in simple capacitive circuits. In electrostatic discharge (ESD), we find the drop in spark resistance is limited by the initial stored charge in the system. For a simpler ESD model (spark resistance in series with the electrode capacitance), we obtain the analytical solutions for a spark resistance model of a general integral form, consisting of the time integral of the current raised to an arbitrary power. We also consider a circuit with an additional fixed “victim” resistance in series with the spark resistance, and capacitance. Here, although the general case requires numerical solution, it is possible to find asymptotic limits for the case of the Rompe and Weizel spark model. Our analysis provides insights into system response that can, for example, be used to evaluate risk zones of parameter space for ESD protection. [ABSTRACT FROM AUTHOR]

The multigap gas switch has been widely used in liner transformer drivers (LTDs), but there is still room for improvement on its self-breakdown and triggering characteristics. In this paper, based on the circuit model of the six-gap gas switch, the gap voltage distribution during the charging and triggering process is analyzed, and the optimization on self-breakdown and triggering characteristics by mounting resistors and capacitors in parallel with switch gaps are theoretically and experimentally investigated. The results indicate that compared with the original switch, when the self-breakdown voltage is about ±90 kV, the standard deviation is reduced from 7.5 to less than 3 kV; for a charging voltage of ±80 kV and by operating at 60% working coefficient, when the negative trigger voltage is 75 kV, the jitter of the switch is reduced from 6.1 to 1.4 ns. [ABSTRACT FROM AUTHOR]

In this paper, a new circuit model is proposed to simulate plasma-induced damage (PID). It includes the two sheaths of the plasma, the blocking capacitor, and the RF power source coupled with the victim device. As a result, this model accounts for both the ac behavior of the plasma and the local voltage imbalance induced by differences in shading factors. The advantage of this approach, compared with the previous works, is that it can yield the waveform impinged by the plasma on the transistor gate, which is known to influence the amount of reliability degradation experienced by the device. Finally, this model is also utilized to elucidate the impact of a parasitic capacitance connected to the transistor gate on the extent of the PID inflicted on the victim device. [ABSTRACT FROM AUTHOR]

Helical coil electromagnetic launchers (HEMLs) using motion-induced commutation strategy solve the problem of synchronization control perfectly. HEMLs have the advantages of symmetric structure, high load impedance, and high energy conversion efficiency. If the structural and launch parameters can be designed reasonably and multiobjective optimization of the velocity, efficiency, and power can be achieved, HEMLs can meet the requirements of multimission applications such as the highvelocity coilgun, electromagnetic mortar, and electromagnetic catapult. In this paper, an improved adaptive genetic algorithm (AGA) based on the solution-reservation strategy to solve the multiobjective optimization problem for HEMLs is presented. The circuit model of the HEML is established and the governing equations are derived. The circuit parameters such as projectile mass, resistance, inductance, and inductance gradient are calculated according to the structural parameters of coils. The classical Runge--Kutta method and the trapezoidal quadrature formula are used to solve the governing equations, besides deriving the velocity, efficiency, and power of the launcher. The AGA is developed in MATLAB. The range of the launch voltage U is 500-5000 V and the number of turns N in coils is 1-500. After the evolution of 14 generations, five noninferior solutions subject to the constraints of temperature rise, launch time, and length are obtained. These different HEML structures can satisfy many different launch applications [ABSTRACT FROM AUTHOR]

The primary test stand (PTS) is a high-current accelerator for Z-pinch experiment at China Academy of Engineering Physics. In this paper, a circuit model for its magnetically insulated transmission lines (MITLs) have been developed, in which all the PTSs transmission line (TL) sections from water TLs, to vacuum insulator stack, to both outer and inner MITLs, and eventually to a wire array load, have been treated as a total of 273 TL elements with different transit time and impedance, among which are comprised of 195 MITL elements. With the aid of the model, the performance of all these sections have been predicted and discussed, including conducting current, interface voltage, loss current, flow impedance, and grounded resistor of each MITL element, as well as the dynamic characteristics of the wire array load. The reliability and accuracy for all these predicted results will await the examination of future experiments. [ABSTRACT FROM PUBLISHER]

Based on the transmission line code (TLCODE), a 1-D circuit model used for the analysis of magnetically-insulated induction voltage adders (MIVAs) was developed. Using cells improved from those of the JianGuang-I facility, a 10-stage MIVA was conceptually designed, and its equivalent TLCODE circuit model was described in detail with consideration of the magnetic insulation. To verify the effectiveness of this model, simulation results were compared with those of a PSPICE model (with no electron emission) under both synchronously triggering mode and ideal time-sequence triggering mode. The comparisons show that calculation results of these two models are accord with each other perfectly (within 0.1%). In addition, features of the calculation results were particularly analyzed and verified by the existent literatures. Considering the magnetic-insulation process, the inner stalk of the 10-stage MIVA was designed, and its output parameters were simulated with various electron emission thresholds (150, 200, and 250 kV/cm). Furthermore, qualitative analysis was done to present the model’s abilities of the magnetic-insulation treatment. [ABSTRACT FROM PUBLISHER]

Much of the work in the area of surface flashover of the past few decades has been devoted into determining which parameters are important in predicting flashover behavior, and the theoretical understanding involved in the process is not yet mature. In this paper, the flashover performance of the insulator in vacuum was studied in the UV-laser-illuminated case. A testbed comprised of a pulsed high-voltage supply, a vacuum chamber, and an excimer laser was assembled to test the flashover performance under pulsed-voltage and UV-laser irradiation. Two different voltage decrease patterns were measured, implying some underlying information of the flashover mechanism. In addition, a circuit model was used to simplify the surface flashover system, and the simulation results seem pretty good with the experimental results. [ABSTRACT FROM PUBLISHER]

In this paper, a theoretical model for the analysis of effective-discharge parameters in a high-power transversely excited atmospheric pressure CO2 laser with an electron beam preionization system is presented. The laser-discharge active volume and electron gun are modeled by nonlinear time-varying impedance. The lumped linear RLC circuits approximate the Marx generator and sustainer bank systems. By this method, the governing equations are reduced to a system of nonlinear time-varying ordinary differential equations that are solved numerically. Based on these equations, the electron beam and the main discharge parameters are evaluated. Our theoretical results are in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Pulsed-power hydrodynamics (PPH) is an evolving application of low-impedance pulsed-power technology. PPH is particularly useful for the study of problems in advanced hydrodynamics, instabilities, turbulence, and material properties. PPH techniques provide a precisely characterized controllable environment at the currently achievable extremes of pressure and material velocity. The Atlas facility, which is designed and built by Los Alamos National Laboratory, is the world's first, and only, laboratory pulsed-power system designed specifically for this relatively new family of pulsed-power applications. Atlas joins a family of low-impedance high-current drivers around the world, which is advancing the field of PPH. The high-precision cylindrical magnetically imploded liner is the tool most frequently used to convert electromagnetic energy into the hydrodynamic (particle kinetic) energy needed to drive strong shocks, quasi-isentropic compression, or large-volume adiabatic compression for the experiments. At typical parameters, a 30-g 1-mm-thick liner with an initial radius of 5 cm and a moderate current of 20 MA can be accelerated to 7.5 km/s, producing megabar shocks in medium density targets. Velocities of up to 20 km/s and pressures of > 20 Mbar in high-density targets are possible. The first Atlas liner implosion experiments were conducted in Los Alamos in September 2001. Sixteen experiments were conducted in the first year of operation before Atlas was disassembled, moved to the Nevada Test Site (NTS), and recommissioned in 2005. The experimental program resumed at the NTS in July 2005. The first Atlas experiments at the NTS included two implosion dynamics experiments, two experiments exploring damage and material failure, a new advanced hydrodynamics series aimed at studying the behavior of particles of damaged material ejected from a free surface into a gas, and a series exploring friction at sliding interfaces under conditions of high normal pressure and high relative velocities. Longer term applications of PPH and the Atlas system include the study of material interfaces subjected to mul-timegagauss magnetic fields, material strength at high strain rate, the properties of strongly coupled plasmas, and the equation of state of materials at pressures approaching 10 Mbar. [ABSTRACT FROM AUTHOR]