Inductive Pulsed Power System Research Articles

Influence of gap length on the gas‐puff z‐pinch plasma produced by an inductive pulsed power system

AbstractIn this study, an argon gas‐puff z‐pinch plasma was produced by an inductive pulsed power system. The gap length dependence of plasma characteristics such as the pinch plasma behavior, soft x‐ray emissions, and spatial distribution of hot spots, was investigated. The soft x‐ray output decreased with gap length, and hot spots generated by sausage instability were distributed along the z‐axis for shorter delay times of the discharge onset. However, hot spots were distributed in the center of the gap space with increased delay times, regardless of the gap length, and the number of hot spots decreased. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 144(4): 1–8, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10126

誘導型パルスパワー方式によるガスパフZピンチプラズマの生成におけるギャップ長の影響

In this study, Ar gas-puff z-pinch plasma is produced by an inductive pulsed power system. Gap length dependency of the z-pinch plasma characteristics such as a pinching plasma behavior, soft x-ray emissions, spatial distribution of hot spots is investigated. The soft x-ray output is increased with the gap length and hot spots generated by the sausage instability is distributed along the z-axis in case of shorter delay time of the discharge onset. However, hot spots are distributed in the center of the gap space with the increase of the delay time in any gap length and the number of hot spots is decreased.

Reduction of the source size of gas-puff z-pinch plasmas using an inductive pulsed power system

A small scale inductive pulsed power (IPP) generator with copper wire fuses as an opening switch has been applied to an argon gas-puff z-pinch plasma which can be used as a point source for x-ray lithography. The IPP generator with fuses supplies a driving current of 60 kA in 400 ns to the z-pinch plasma. Without fuses, the generator serves as a conventional fast bank (FB) system which supplies z-pinch current of 60 kA in 4.5 μs. Characteristics of the z-pinch implosions in IPP and FB systems are investigated and compared. The result obtained shows that the intensity of soft x rays emitted from hot spots in both systems is decreased gradually with longer delay time, which is the time difference between energizing a gas-puff actuator and a primary current trigger. Dual axis pinhole imagery shows that the hot spot size is 0.8 mm in diameter in both systems. However, the average radial displacement of hot spots is 0.9 mm in the FB system and it is reduced to 0.4 mm in the IPP system. Optical framing camera images have confirmed that the radial distribution of hot spots is due to kink instability. The framing images also show that the imploding plasma in the FB system which has a pinch size of 2.2 mm in diameter can be further compressed to 1.3 mm. The IPP system can suppress the kink instability of pinch plasma and increases plasma column uniformity along the z axis. This suggests that the IPP system can improve the stability of the pinched plasma so as to minimize the end-on source size for x-ray lithography applications.

80-kW inductive pulsed power system with a photoconductive semiconductor switch

The performance of the GaAs photoconductive semiconductor switch (PCSS) has been optimized in the current-charged transmission-line configuration to produce a power gain of 45 with an output pulse of 80 kW. The fast falltime of the switch resistance produced by the specially tailored optical pulse that actives the PCSS is mainly responsible for the high power gain achieved. An effect similar to lock-on was found to limit the output voltage to approximately 2 kV.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Review of Plasma Flow Switch Development

The plasma flow switch utilizes the nonlinear and nonuniform dynamics of a plasma discharge in vacuum to accumulate magnetic energy in times of several microseconds and then release this energy to a load in times of a few hundred nanoseconds. Experiments have been performed with capacitor banks up to 6 MJ, providing currents in excess of 107 A and peak voltages over 0.5 MV. Theoretical models include simple slug dynamics coupled to lumped-circuit analyses, magnetoacoustic considerations of one- and two-dimensional aspects of the plasma flow, and two-dimensional magnetohydrodynamic code calculations. The present article reviews both experimental and theoretical efforts, discusses the use of the plasma flow switch to drive plasma liner implosions and high-energy ion flows, and indicates directions for plasma flow switch applications to very high current, high-energy inductive pulsed power systems.

Theoretical modeling of electromagnetically imploded plasma liners

The generation of high-energy-density plasmas by the electromagnetic implosion of cylindrical foils (i.e., imploding plasma shells or hollow z-pinches) has been explored analytically and through numerical simulation. These theoretical investigations have been performed for a variety of foil initial conditions (radius, height, and foil mass) for both capacitive and inductive pulsed power systems. The development of the theoretical modeling techniques is presented, covering both circuit models and plasma load models. The circuit models include simple single loop capacitive and multiple loop inductive systems. These circuits are coupled to the imploding plasma loads whose response has been studied by models ranging from simple time varying inductances to complex two-dimensional magnetohydrodynamic numerical simulations. Results from a series of configurations are given, showing the development of modelling techniques used to study the dynamics of the plasma implosion process and the role of instabilities. Interaction between analytic techniques and detailed numerical simulation has led to improvement in all theoretical modeling techniques presently used to study the implosion process. Comparisons of implosion times, shell structure, instability growth rates, and thermalization times have shown good agreement between analytic/heuristic techniques and more detailed two dimensional magnetohydrodynamic simulations. These in turn have provided excellent agreement with experimental results for both capacitor and inductor pulse power systems.