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This article introduces an optimal design method for a multistage induction coil launcher. Considering the magnetic coupling and the effect of the armature’s resistance, the basic criteria to select the structure of the driving coil and armature are proposed, and the genetic algorithm is introduced to optimize the pending parameters. Based on the principle that the current in the driving coil matches the movement state of the armature, the design method of optimal capacitor parameters is deduced. The results show that the design error is less than 1%. For a multistage induction coil launcher, the optimization is carried out stage by stage. The effect of the stage spacing between driving coils is analyzed, and it is found that changing the direction of the current in driving coils helps to improve the system efficiency. Finally, based on the above optimal design method, a multistage induction coil launcher is designed, and the energy conversion efficiency of the system is close to 40%. [ABSTRACT FROM AUTHOR]

We describe the design, operation, and qualification of a coaxial plasma gun (CPG) in a low-pressure environment with a gas puff inlet. This infrastructure enables a CPG to operate in the deflagration mode followed by snowplow plasma sheath formation. These modes inject radially expanding and axially propagating plasma sheaths into a low-pressure residual background. This manuscript details the pulse power delivery circuit, including automatic logic control of subcircuits. High-speed camera images (12800 frames/s) of the formed plasma elucidate the ionization of an axially propagating plasma. Long-exposure images (1.3 s) capture the full propagation distance of the plasmoid. Rogowski coil current diagnostics elucidate the timing of a self-crowbar discharge that delineates between deflagration and snowplow modes. An empirically determined 50-ms gas puff duration resulted in a maximum plasma propagation distance of $\approx 23$ cm. Shorter durations did not ionize a sufficient amount of gas for elongated axial propagation, whereas longer durations suppressed axial plasma sheath expansion. This type of gas injection CPG device is now qualified for use in CPG experiments that require the snowplow mode and maximum mean free path of fast ions resulting from various plasma heating mechanisms. These include CPG operation within external magnetic fields in which significant plasma propagation distance is required, including solar physics experiments and space propulsion development. [ABSTRACT FROM AUTHOR]

The results of comparative studies of two compact generators of nanosecond high-voltage pulses are presented. Both generators include an opening switch in the form of a block of drift step-recovery diodes (DSRDs) and a closing switch in the form of a block of shock-ionized dynistors (SIDs). The generators are designed according to two different schemes, but they have similar parameters of the output pulses on a load of $50~\Omega $ : the amplitude of the output voltage is ~ 30 kV, its rise time is ~ 3 ns, and the output energy is ~ 0.4 J. It is shown that it is possible to increase the output voltage and output energy of the generators. [ABSTRACT FROM AUTHOR]

As energy storage elements in modular multilevel converter (MMC) sub-module of a unified power flow controller (UPFC), metallized film capacitors endure ac and dc superimposed voltages, which brings new challenges to insulation performance of the dielectric film. In this article, an experimental setup was created to investigate the breakdown characteristics of the dielectric film for sub-module capacitors. Factors which may affect breakdown strength under ac and dc superimposed voltages were studied experimentally. The results reveal that, as the dc voltage component increases in the range of 0–3200 V, the breakdown strength gradually increases by 16.36%; as the ac voltage component increases in the range of 0–1800 V, the breakdown strength slightly decreases by 3.52%; the breakdown strength is more affected by frequency as the ac voltage component increases and decreases with increasing frequency; as temperature increases from 20 °C to 95 °C, the breakdown strength substantially decreases by 31.12%; as the thickness of the film increases from 7 to $10~\mu \text{m}$ , the breakdown strength slightly increases by 6.32%. For capacitors in 500-kV UPFC, the dc voltage component is approximately 1600 V; the ac voltage component, whose peak-to-peak value is within 800 V, mainly contains power frequency and the second harmonic components. According to the experimental results, since the ac voltage component is small and the order of harmonic is low, the breakdown strength of capacitors in UPFC has little difference compared with that of the dc capacitors. This article can provide a reference for insulation design optimization of capacitors in UPFC. [ABSTRACT FROM AUTHOR]

The development of pulsed power puts forward new requirements on volume and weight of generators. To develop a compact and lightweight high-voltage pulse generator, this work proposed a new modular pulse forming topology with high voltage gain and a reduced number of energy storage capacitors. The topology is realized by charging a set of capacitors cyclically step-by-step and discharging repetitively in series. A voltage gain of $2^{n-1}$ can be achieved with $2n\,+\,1$ all-solid-state switches, $n$ fast recovery diodes, and n capacitors. An experimental prototype built around five capacitors generates high-voltage pulses with adjustable voltage level, pulse frequency, and pulsewidth. Meanwhile, it is verified that the prototype has a certain capacity with a capacitive load. [ABSTRACT FROM AUTHOR]

Reconnection electromagnetic launcher is a kind of electromagnetic launcher, which has excellent performance of launching. The change of projectile width has a great influence on the launching efficiency of reconnection electromagnetic launcher. The influence of the reverse vortex generated on both sides of the projectile on the launch efficiency when the projectile width increases is studied in this article. First, the model and basic principles of the reconnection electromagnetic launcher are introduced, and then the electromagnetic finite-element software is used to carry out a large number of simulations to study the launch model. The results show that when the projectile weight is kept constant by digging out a part of the projectile, and the projectile width increases within a certain range, the launch efficiency will increase as the width of the projectile increases, the increasing trend is smaller and smaller, and finally it will gradually decrease. When the mass of the projectile is determined, there is an optimal width. Finally, the eddy current distribution in the projectile is analyzed, and it is found that when the projectile has a wide width, the eddy current opposite to the eddy current in the middle of the projectile will appear on both sides of the projectile. Through the analysis of electromagnetic force, it can be concluded that the reverse eddy current is beneficial to the launch. Therefore, when keeping the weight of the projectile constant and only increasing the width, the efficiency will gradually increase. When the width of the projectile is highly wide, the excavated part of the projectile is very large, which starts to affect the vortex distribution and reduce the efficiency. This research provides a reference for the design of the projectile of the reconnection electromagnetic launcher. [ABSTRACT FROM AUTHOR]

Long pulse gas lasers utilizing double-discharge circuits are different from the single-short pulse gas lasers in that they do not require all of the desired energy to be deposited into the peaking capacitors prior to ignition of the main gap. Instead, the majority of the energy is held in another capacitor that is then discharged in the form of a longer duration discharge pulse output compared with that of single-short pulse lasers. Extended stability of the discharge is typically achieved by igniting the main gap discharge at higher ignition voltages. Several double-discharge circuit topologies exist in the literature. However, each topology has its own disadvantages primarily centered around the components needed and the resulting complexity. In this article we introduce the application of the new hybrid circuit pulsed power topology as a double-discharge circuit with high ignition voltages. The hybrid circuit pulsed power topology was originally published by the authors of this article in their previous publication titled “A New Hybrid Pulsed Power Circuit Topology for Gas Laser Applications.” The advantage of the hybrid circuit as a double-discharge circuit is that it does not require any special device [e.g., semiconductor opening switch (SOS) diode] and can use commonly available components. [ABSTRACT FROM AUTHOR]

Marx generators are widely used to produce transient high-voltage pulses. The evolution of semiconductor devices and power electronics concepts promotes the development of solid-state Marx generators (SSMGs) and enables them with flexible pulse modulation ability. First, this article sorts out the evolution of SSMGs topologies chronologically. We can see that how the energy efficiency of SSMGs is considerably improved by replacing resistors with diodes and switches and how square-wave pulses are generated by SSMGs based on half-bridge structures. Unipolar and bipolar pulses can be easily produced with different SSMGs. Second, we discuss the influence of rated voltage and rated power of present semiconductor switches on the performances of SSMGs since switches are the key components in pulse generators. To reduce the size and weight of SSMGs, metal–oxide–semiconductor field-effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs) with small packages are preferable. Third, synchronous isolated driving of switches as the crucial technique in SSMGs is introduced. Different methods of providing synchronous signals and isolated power to various stages in SSMGs are illustrated. Fourth, the performance including load capacity, droop compensation, waveform modulation, and self-triggering of SSMGs is discussed. In the end, the developing trend of SSMGs is given. [ABSTRACT FROM AUTHOR]

A major decision surrounding the design of pulsed power circuits for gas lasers is the choice between a thyratron and solid-state switches. The thyratron is a mature device technology whose cost is increasing. The ratings of solid-state switches still do not match those of a thyratron. Pulse transformer and pulse compression circuits must be added to overcome the lower ratings of solid-state switches leading to a higher parts count and cost. This article proposes a new solid-state pulse power topology called the hybrid circuit topology to address the parts count and cost issue. The hybrid circuit makes use of a combination of capacitive and inductive energy storage to reduce the time required to transfer the energy from the transformer primary to the secondary side. This ultimately reduces the quantity of magnetic material used in the pulse compression circuit. [ABSTRACT FROM AUTHOR]