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Railguns are current-driven guns that allow reaching large muzzle velocities and energies. In the military context, the long-range artillery scenario makes use of these two capabilities to enable the launch of hypervelocity projectiles to target distances above 100 km. As of today, the most advanced railgun project is conducted by the Office of Naval Research, Arlington, VA, USA, and features railguns with a muzzle energy of 32 MJ. Such large artillery railgun systems with efficiencies above 30% are fed by a pulsed power system with a nominal energy content of about 100 MJ. In contrast to this, experiments with French-German Research Institute’s (ISL) most powerful railgun, PEGASUS, have reached muzzle energies of 2 MJ, only. The nearer future ISL has to answer two questions: 1) is the railgun technology adequate for a long-range artillery scenario? 2) can the railgun launch a hypervelocity projectile which is being developed by other groups in ISL? To do so and to support the development of the hypervelocity projectile, a larger railgun installation with a significant increase of the energy and free flight capability is required. In this paper, three different railgun systems were investigated using an electric circuit simulation code. The systems are referred to by the energy being stored in the capacitors as 25, 50, and 100 MJ. The aim of this paper is to investigate what masses can be accelerated to the relevant velocity range for the long-range artillery scenario by these different primary energies. The results of this paper can be used to aid the decision about the required size, with respect to the military scenario, of a potential future railgun system. [ABSTRACT FROM AUTHOR]

This paper proposes a novel single-stage double-layer saddle multipole field electromagnetic launcher (SSDFEL), which combines the characteristics of reconnection gun to achieve simultaneous linear acceleration and gyroscopic stabilization of the projectile. Since the saddle driving coils are divided into two layers, the magnetic field density inside the launcher is enhanced. The eddy current induced on the inner and outer surfaces of the projectile is greatly changed by the hollow cylindrical projectile with six symmetrical vertical slots twisted at a certain angle, and the projectile is simultaneously propelled to perform rotation motion and linear motion. In this paper, the electromagnetic field finite-element software is used to simulate and calculate this model. The simulation results indicated that the double-layer driving coil distribution has larger axial acceleration force and bigger circumferential torque than that of the single-layer driving coil distribution, the energy conversion efficiency has also been obviously increased, and there is an optimal initial twisted angle, which accelerates the projectile to the peak of rotation. To verify the results, an SSDFEL was established and tested. The experiment results confirm that the rotation performance can be affected by the initial twisted angle and a better launching effect is achieved than a single-layer distribution. In general, the experimental results are in agreement with the simulation results. [ABSTRACT FROM AUTHOR]

In this paper, the capacitances of the two-stage bushing that is installed in the 1-MV test bed for neutral beam injectors in the future fusion reactors are calculated by modeling the bushing in a 3-D electrostatic code. One of the modeling results is the stored energy in the bushing, which corresponds to 1/2 CV2. After evaluating the bushing capacitance, a MATLAB/Simulink model is presented to model the possible breakdown in the bushing and between the electrodes in the 1-MV test bed. When a breakdown occurs between anode and cathode, an overcurrent is drawing that can cause damage in the electrode surfaces while an overvoltage takes place when the breakdown happens between the bushing stages. Such damage has been observed experimentally in the past. This paper also presents some of the possible protection against the breakdown in the 1-MV test bed to dissipate the stored energy in order to protect the electrode surfaces and the bushing. The suggested protections presented in this paper are damping resistors, surge arrester individually, and both of them. Also, a coil can be added to the DR either in series or in parallel. [ABSTRACT FROM AUTHOR]

This paper proposes unconventional control techniques for a portable power supply consisting of electric double-layer capacitors (EDLCs), a dc–dc converter, and a low-impedance load such a plasma load. Between the EDLCs and the plasma load consuming high power, a dc–dc converter is required to control the output voltage from the rapidly decreasing voltage of EDLCs. In addition, the dc–dc converter should maintain a set point by responding to arcs occurred in plasma process. This paper proposed hybrid analog and digital controls for a nonideal boost converter which was setup by theoretical analysis. The proposed system is verified with experiment and simulation. As a result, the proposed control method can maintain the constant output voltage longer than a traditional analog pulsewidth modulation control. [ABSTRACT FROM AUTHOR]

This paper discusses a novel methodology to increase the voltage droop compensation range in generalized solid-state bipolar high-voltage Marx modulators with one resonant stage. To maintain the modularity characteristic of bipolar Marx modulators, the imbedding of additional resonant stages is not straightforward. Nevertheless, this paper proposes to add a second resonant stage to the already existing resonant-type voltage droop compensation stage. This second stage increases the voltage droop compensation percentage of a generalized solid-state bipolar Marx generator. The compensation of the bipolar pulse voltage droop is now achieved by adding two auxiliary synchronous compensation resonant voltages, to the output capacitive decaying voltage. Simulation and experimental results are presented for six Marx plus two resonant stages, 16% voltage droop, with 3-kV pulse amplitude, 100- $\mu \text{s}$ pulsewidth, 40-ms relaxation time, and 10-Hz pulse repetition rate. [ABSTRACT FROM AUTHOR]

In order to generate high-voltage high-pulsed power, klystron modulators necessarily contain at least one capacitor bank charging structure supplying the energy to be released during the pulse. Conventional charging structures are based on ac/dc front-end units typically based on diode rectifiers combined with power charging structures operated in on/off mode as a second stage, producing prohibitive levels of grid flicker and harmonic contents on the ac grid side while operating at suboptimal power factor. These problems are usually corrected by both costly and spacious external grid compensators. Today, the increased demand on both accelerator peak power and pulselength (translating into higher average power), in conjunction with stricter regulations and standards represent additional challenges also in modulator design. An alternative method for capacitor bank charging, in a steady state allowing for the complete reduction of grid flicker as well as ac line current harmonics and reactive power, was presented by the authors in a preceding publication. This paper presents in further detail the benefits of the proposed power electronic structure and associated control scheme in the context of a review of other solutions suggested for constant power charging and flicker mitigation. This paper also contains a complete description of the proposed control scheme as well as further experimental results, including a thorough assessment of its performance under transient conditions. All experimental results were obtained on a klystron modulator prototype rated for long pulses (3.5 ms), high voltage (115 kV), and high pulsed power (peak power > 2 MW). [ABSTRACT FROM AUTHOR]

This paper presents the design and construction of a sample of Marx pulsed generator based on boost converter (BC) pulse-forming networks (BCPFNs). BCPFN is used instead of the conventional Marx floors for constructing this pulsed generator. BCPFN is carried out by connecting inductors and capacitors in series and parallel modes, respectively, by using solid-state switches, and during this procedure the pulsed generator converts to BC temporarily and increases the voltage of capacitors uniformly to a considerable value. This technique causes an increase in the discharging voltage level to the load that is many times more than its dc voltage source by charging the capacitors to a greater level. In order to take advantage of the benefits of Marx generator and PFN, this paper suggests a new circuit with the minimum number of switches. It means, to compose BCPFN and Marx, we have tried to design the circuit with fewer switches and instead of it we have achieved our desired performance with changing the operating mode in the states of BC, PFN, BCPFN, and BCPFN Marx. The results are simulated with MATLAB software. At the end, the experimental results of the construction of the above-mentioned system at low-power levels are presented, and the topology’s accuracy is proved by comparing them to the results of simulation. [ABSTRACT FROM AUTHOR]

This paper discusses the control of a modular multilevel converter (MMC) used as a grid interface for the klystron modulators in the compact linear collider (CLIC). The converter has a DC side load which takes short-duration power pulses, causing high DC side power fluctuations that are not tolerable if seen by the AC grid. The DC–AC power decoupling capability of the MMC enables mitigation of the power ripple on the AC side, guaranteeing compliance with power quality requirements. However, the pulse repetition rate of the CLIC modulators is synchronized the 50-Hz AC grid and this induces permanent power imbalance in the arms of the MMC, causing voltage deviation and overmodulation unless appropriate balancing strategies are implemented. Unlike existing arm balancing methods that control 50-Hz circulating currents to balance the arm powers, the method proposed in this paper introduces an augmented modulation strategy where modulation signals are redistributed among arms based on the demand from a balancing controller. The resulting controller has lower complexity and its simple structure enables an easier design of the balancing loop, which guarantees predictable dynamics in operation. The effectiveness of the method has been demonstrated in simulation for the full-scale CLIC converter ratings and experimentally on a 7-kW MMC prototype operating with a 3.3-kA pulsed DC load. [ABSTRACT FROM AUTHOR]

A new modular pulsed-power source with fast rise time and step-wise arbitrary output waveform generation is currently under development to drive the Gepulste Elektronenstrahlanlage device investigated at the Institute for Pulsed Power and Microwave Technology (IHM). Acknowledging the complex design procedures necessary to set up a modular pulsed-power source for voltages of up to 120 kV, this paper focuses on the circuit design for a single stage and its validation prior to the generator assembly. Using a semiconductor-based Marx generator topology, the stages are designed to have an output voltage of 1 kV with a pulse current of up to 600 A. When connected to an ohmic load, the measured current rise times are in the order of 46 ns resulting in the current rise rates of up to 10 kA/ $\mu \text{s}$ using the commercial devices. The step-wise arbitrary output waveform is created by generating the switching commands on the stage using a microprocessor and a fast optical synchronization unit. Effective stage shielding is verified by operating the stage in a 100-kV, 2.5-kA electromagnetic interference test bed. This paper presents the design considerations and the corresponding measurements. [ABSTRACT FROM AUTHOR]

The linear induction launcher consists of two parts: the barrel section and the projectile section. The barrel contains of a long coaxial sectionalized group of coils that are energized by a capacitor bank or generator sets. This paper deals with the design, implementation, and experimental test of a coreless axial-flux permanent magnet (AFPM) pulsed alternator with a flywheel system as an energy source for linear induction coil launchers. The proposed coreless AFPM generator has a low internal inductance and resistance of stator windings without compensation windings when compared with the conventional iron core machines. This paper describes the coreless AFPM generator configuration and shows the simulation findings. [ABSTRACT FROM AUTHOR]

The trend to move toward the solid-state and repetitive pulsed power supply requires the high-voltage, high-current, and high-speed semiconductor devices, which makes an insulated gate bipolar transistor (IGBT) preferred for this application. However, as a bipolar device, the IGBT is limited by the switching speed and switching loss. In this paper, the potential of silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET) for the pulsed power application is investigated. The surge current capabilities of 1.2-kV, 30-A commercial Si IGBT and SiC MOSFET are characterized and compared by the capacitor discharge experiment. In addition, the effects of various circuit parameters, including gate resistance, dc-link voltage, and dc-link capacitance, on the capacitor discharge process are investigated. It is found that the pulse current of SiC MOSFET is around two times of Si IGBT, which achieves good agreement with the datasheet. Using $di/dt$ to represent the discharging speed, the SiC MOSFET is 10 times faster than the Si IGBT. It is because the SiC MOSFET shows a lower ON-resistance in the saturation region resulted from the short-channel effect. This paper confirms the high-speed and high-current advantages of SiC MOSFET in the pulsed power application. [ABSTRACT FROM AUTHOR]

A novel high-voltage direct current (HVdc) power supply which has no transformer or voltage multiplier circuit is presented and analyzed in this paper. This is made possible upon the diodes storage delay phenomenon. This proposed power supply is compact, lightweight, and low cost. Its basic structure includes a diode with a proper reverse recovery specification that plays the role of a step-up transformer in the conventional HVdc supplies and a high-voltage capacitor which stabilizes the output voltage. This structure has remarkable advantages over the conventional transformer-based HVdc supplies, such as compactness, a low ripple output, and a low-cost power supply. Performance of the proposed method and its accuracy are investigated in this paper. The results are verified by implementation of a 1.2-kV prototype supply. [ABSTRACT FROM AUTHOR]

In this paper, a new structure of Marx generator (MG) based on buck--boost converter is proposed to generate high-voltage pulses. In this structure, a single-phase inverter is employed to supply parallel diode--capacitor units by positive and negative values of the input dc source (±Vin). The main contribution of this paper is proposing a new switching strategy, by which a group of capacitors are charged properly. Finally, the charged capacitors are connected in series such that the output voltage is equal to summation of the capacitors' voltages. Considering specified value of the output voltage, the number of circuit elements in the proposed structure is reduced in comparison with other topologies of unipolar MG. Furthermore, voltage rating of switches and diodes in the proposed topology is lower than that of other unipolar MG structures. Design of the structure ensures that there is no need to connect the switches in series, when the number of stages is increased. To verify the performance of the proposed MG structure, simulation has been carried out in MATLAB/Simulink. Furthermore, a prototype of the proposed structure has been implemented in the lab. The simulation and experimental results confirm the capability of the structure for generating high-voltage pulses. [ABSTRACT FROM AUTHOR]

This paper investigates the dynamic dielectric recovery synergy (DDRS) of hybrid circuit breakers (HCBs) with CO2 gas and vacuum gaps in series. The interaction between the vacuum arc and CO2 gas arc is simulated by the continuous transient arc model and Mayr arc model. The simulation results indicate that the extra methods, for example, dividing capacitors, are needed to obtain optimal DDRS of HCB. The prototype of HCB and the test circuit are established. The influence of the coordination of arcing time, dividing capacitors, and the CO2 gas pressures on the transient recovery voltage (TRV) distribution and the breaking capacity is investigated. The differences of HCBs with SF6 gas and CO2 gas are also compared. According to the results, favorable DDRS in HCB can be obtained in the condition that the vacuum gap endures the initial TRV while the following major TRV distribution is mainly depended on the dynamic dielectric in CO2 gas gap. However, the dynamic dielectric recovery of CO2 gas gap is limited by the structure of rotating arc CO2 gas interrupter in this paper. In the future, the interruption capacity of HCB based on CO2 gas can be improved by synergy control, as the development of CO2 gas circuit breakers. [ABSTRACT FROM PUBLISHER]

This paper presents the effect of stray capacitances in bipolar (negative and/or positive) pulses generated by the two different topologies of the solid-state Marx modulators. According to the analysis, the stray capacitances influence the energy transfer from the Marx modulator capacitors to the load affecting the bipolar (negative and/or positive) pulse rise time. This paper deals with the structure design to reduce the influence of the stray capacitance and to improve the pulse rise time of these bipolar solid-state Marx modulators. A four-stage laboratory prototype of the two topologies has been assembled using 1200-V insulated gate bipolar transistors and diodes, operating with 1000-V dc input voltage and 1-kHz frequency, producing 4-kV bipolar pulses, with 5- \mu \texts pulse duration and 120-ns rise time, into a resistive load. [ABSTRACT FROM PUBLISHER]

This paper addresses the design of a solid-state bipolar pulsed-power modulator based on a series of stacked power cells that realize a simple and robust structure. Each cell is charged in parallel by an LCC resonant converter independently of the discharging loop. A passive cell-balancing design is implemented. The power cell using insulated gate bipolar transistors (IGBTs) can operate in bypass mode without an additional component, and the circuit operation was analyzed. A simple gate driving method, which provides synchronized gate signals without an extra power source of each gate driver using two control loops and isolation transformers, is implemented for the proposed bipolar pulsed-power modulator based on stacked cells. Moreover, an unexpected gate turn-on problem was solved by an additional off signal. To validate the proposed structure and the gate driving scheme, a three-cell, 1.2-kV, 110-A, 1.5- to 4- $\mu \text{s}$ , 3-kHz laboratory experimental prototype test was conducted. The results proved the reliability of the proposed solid-state bipolar pulsed-power modulator. [ABSTRACT FROM AUTHOR]

This paper proposes a flyback-circuit-based design of a trigger circuit for a high-power gas switch. By incorporating a flyback circuit in a high-power gas switch, it is possible to generate a high step-up ratio and high-voltage pulse by using a transformer. Furthermore, simple trigger circuit having the minimum possible number of components (transformer and switch) can be realized. When an inductor is used as an energy storage element, energy is stored as a current source, and thus, the element can operate reliably when low impedance exists between the trigger node of the switch after triggering. According to the fundamental operating principle of a flyback circuit, the proposed trigger circuit is designed considering the maximum trigger voltage and energy required for a high-power gas switch. To verify the proposed design procedure and feasibility of the trigger circuit, a compact trigger circuit (7.5 kV, 1.3 mJ/pulse) is simulated using the PSpice program and implemented. Based on this compact circuit, a trigger circuit (20 kV, 100 mJ/pulse) for a triggered vacuum switch (TVS) is developed, and the tests with an actual TVS (3.3 kJ) are carried out. [ABSTRACT FROM AUTHOR]

With pancake-coil electromagnetic launcher as a research object, the experimental platform of the pancake-coil electromagnetic launch intercepting system with 50-kV pulse capacitors as energy storage was built and tested for discharge to study the electromagnetic launch intercepting system. The oscillation problem of the current flowing through freewheeling loop was solved by connecting the reverse-cut diode stack in series with trigger vacuum switch (TVS). However, due to limiting power component, the experimental system can work normally at 9.4-kV capacitor voltage. A proportional 3-D model of the pancake-coil electromagnetic launcher and an external excitation circuit model were established based on the structural and circuit parameters of the experimental system to perform simulation. The accuracy of the simulation model was proved by comparing the simulated and measured currents obtained under same capacitor parameters. Based on the established finite element model, maximum launching capacity and energy efficiency of the experimental system platform were estimated through simulation, and the space–time distribution characteristics of the magnetic field were analyzed during the launching process. In addition, the electromagnetic-structure coupling simulation was carried out to study the deformation problems of components of launcher by sequential coupling. All the work done in this paper provides guidance for a detail research, and we want to try to improve our electromagnetic launch experimental system. [ABSTRACT FROM AUTHOR]

Recent studies have shown that rectangular high-voltage pulses have a high-performance in dielectric barrier discharges (DBDs). To generate the rectangular pulses used in the Marx generators, the most common way is driving two sets of switches synchronously with a different sequence. Because of the fast-changing current and voltage, the electromagnetic interference (EMI) will affect the circuit. Therefore, if two groups of switches were triggered mistakenly at the same time, it would cause the partial short-circuit phenomenon. In this paper, a new driving circuit with overcurrent protection for the Marx generators is proposed. It used only one synchronous signal to control two sets of switches. Experimental results showed that the short current could be limited within 100 A. The proposed driving circuit was applied to a seven-stage Marx generator, and 5-kV rectangular pulses can be obtained steadily at 1 kHz, which can greatly improve the stability of the system. [ABSTRACT FROM AUTHOR]

This paper describes the operation of a solid-state generator proposed to produce high-frequency bipolar high-voltage pulse bursts on resistive-type loads, intended for medical applications. The generator design is based on two independent solid-state unipolar positive Marx generators positioned back to back, where the load is placed between the outputs of the two generators. SiC metal–oxide–semiconductor field-effect transistors (MOSFETs) are used in order to allow high-frequency operation. A generator with two five-stage Marx generators is experimentally tested in order to deliver up to 5000-V/50-A bipolar pulses, with 500-ns–10- $\mu \text{s}$ pulse widths and 200-ns–10- $\mu \text{s}$ relaxation time between positive and negative pulses. The generator operates in the burst mode from 1 to 200 pulses, in excess of 500 kHz within the burst, which can have a repetition frequency up to 1 kHz limited by the input 1000-V/200-W power supply, with forced air cooling. Results, with resistive-type loads, for several single pulse and burst mode operations are presented and discussed. [ABSTRACT FROM AUTHOR]

In this paper, we report a qualitative model of operation and energy release in pulsed dielectric barrier discharges (DBDs). We demonstrate that pulsed DBDs operate according to the “maximum power principle” and explain the relevant physical processes. Compared to experimental data, the proposed model allows an accurate estimation of the discharge pulse energy as a function of dielectric properties, electrode size, and pulse parameters (shape and voltage amplitude). [ABSTRACT FROM AUTHOR]

A quench protection switch (QPS) is indispensable to protect the magnet coils from the damage of quench in a superconducting Tokamak. In this paper, a QPS based on artificial current zero is involved. The vacuum circuit breaker (VCB), which is driven by a high-speed electromagnetic repulsion mechanism, is used as the main circuit breaker (MCB). Two kinds of commercial vacuum interrupters (VIs), which have contacts generating axial magnetic field (AMF) and transverse magnetic field (TMF), respectively, are applied. The breaking current with an amplitude of 10~25 kA is generated by an LC oscillating circuit. The countercurrent with frequency in the range of 500–3000 Hz is provided by a commutation branch. The interruption performance of the two kinds of VIs under different breaking current and countercurrent frequencies is investigated. The experimental results indicate that the differences in interruption performance under the two types of contacts are increasing with larger frequencies of countercurrents. [ABSTRACT FROM AUTHOR]

The motion of arc between the transverse magnetic field (TMF) contacts gradually slows down and transits to the diffusion mode before the current zero crossing. The process of arc transition to diffusion mode seriously affects the contact surface ablation. However, the influence on vacuum arc transition to diffuse mode has not been deeply studied to date. In this paper, TMF contacts with different structures were investigated in a demountable vacuum chamber that contained a high-speed charge-coupled device video camera. It was found that current, arcing time, and axial magnetic field (AMF) components had significant effects on arc appearance, arc column diameter, and moment and current at which the arc transited to diffuse mode. The transition moment to diffuse mode exhibited a linear relationship with the peak current. The arc energy accumulated before diffuse mode would increase and the transition moment would be advanced when the peak current was increased. The range of the transition current to diffuse mode and small-current diffuse mode remain unchanged with peak current and arcing time. The arc column in the contacts with larger axial self-magnetic field had larger diameter while transiting to diffuse mode and also transited to the diffuse mode earlier and accumulated less energy during the transition. [ABSTRACT FROM AUTHOR]

Because it possesses higher current turn-off capability, the inverse current commutation with semiconductor devices (ICCOS) is a better option for the opening switch of an inductive pulsed power supply than the integrated gate commutated thyristor. This paper investigates the counter-current capacitor, which is the key component that determines the turn-off result and the volume of the counter-current branch. The major contributions of this paper include the following: 1) deriving an analytical expression for the minimum precharged capacitor voltage that can reliably turn off the main switch; 2) verifying this expression through a series of experiments within a current range of 0 to 4000 A and an energy range of 0 to 50 kJ; 3) giving an approximate expression for the optimal capacitance that minimizes the precharged energy; and 4) investigating the variation trends of the optimal capacitance and the corresponding optimal precharged energy with varying inductor current. [ABSTRACT FROM PUBLISHER]

Compulsators are ac generators which are used for electromagnetic launch applications over the past few decades. This paper presents the work carried out by the authors to design a compulsator for a railgun which has been built and tested with a capacitor bank of 20 kJ as the pulsed-power source in the author’s laboratory. The generator topology selected for the compulsator is a single phase, two-pole machine with iron core and passive compensation. The design is based on the criterion of achieving maximum projectile exit velocity with the additional condition that natural current zero is synchronized with the instant of the projectile’s exit. The effect of varying the different parameters of the compulsator on the performance of the system has also been studied and discussed in this paper. By means of performance analysis, the necessary background for the design of the actual compulsator has also been achieved. [ABSTRACT FROM PUBLISHER]

Based on the urgent needs for modularization and miniaturization of the inductive pulsed power supply system, this paper proposes the conceptual design and comparison of 100-kJ inductive storage power modules including four circuit topologies, three of which are proposed in our previous researches. The four circuit topologies are the STRETCH meat grinder, the XRAM with STRETCH meat grinder unit, the XRAM with strongly coupled inductors, and the XRAM with magnetic flux compression effect. The maximum load current of each constructed module is set to be 50 kA and its pulsewidth is at least 5 ms, which are the same as the main electrical properties of an existing 100-kJ capacitive module. A comparative study on energy density among the constructed inductive modules and the existing capacitive module is carried out in depth. Results show that the inductive modules, considering the volume of semiconductor switches and their control circuits, have higher energy density than that of the capacitive module. Among four constructed inductive modules, the XRAM with strongly coupled inductors module has the highest inductive energy density, and the XRAM with magnetic flux compression effect module has relatively better comprehensive performance. This paper offers the theoretical analysis foundation for investigating the inductive pulse power supply with higher energy. [ABSTRACT FROM PUBLISHER]

Superconducting pulsed-power supply (SPPS) provides an efficient method for both high-density inductive energy storage and high current pulse generation. An SPPS consisting of eight high-temperature superconducting pulsed-power transformer (HTSPPT) modules with XRAM methodology was designed and simulated in preliminary studies. It recycled the leakage flux energy and reduced the voltage across the opening switch with a capacitor in primary. However, the SPPS with XRAM methodology has two problems. The first one is that it can provide high pulse amplitude, but cannot provide enough width. The other one is that the ratio of the maximum capacitive energy over the total inductive energy is relatively large, which cuts down the overall system energy density. This paper proposes a modified topology of SPPS with capacitor reuse methodology. Multiple HTSPPT modules are divided into several groups. Each group shares the same capacitor. The procedure of the modified SPPS is presented in detail. A 270-kJ SPPS with capacitor reuse methodology is designed and simulated to illustrate the modified topology. With the load parameters of a small railgun, the peak value of the load current is 207.15 kA and the pulse half-height width is 5.56 ms, the ratio of the maximum capacitive energy over the total inductive energy is 11%. The characteristics of the modified topology are also described in detail in this paper. [ABSTRACT FROM PUBLISHER]

Repetitive high pulsed electric field (PEF) is an effective method to kill microorganisms and bacteria in water treatment applications. The PEF can be generated by applying high-power electromagnetic pulse across the sample to be treated. There are two main types of high-voltage pulse generators, namely, unipolar and bipolar. In this paper, a full-bridge submodule-based modular high-voltage pulse generator, having the ability to generate unipolar and bipolar high-voltage pulses with different shapes from a relatively low-voltage input dc supply, is proposed. In the proposed configuration, relatively low-voltage insulated gate bipolar transistors (IGBTs) are required to generate the high-voltage bipolar pulses. A thyristor rated at the level of the pulsed output voltage is required in the proposed configuration to bypass the load during the charging process of capacitors. In the proposed approach, a thyristor is used instead of the self-commutated high-voltage switch (e.g., series-connected IGBTs), as thyristors are available with high-voltage ratings and possess inherent reverse voltage blocking capability. A detailed illustration of the proposed configuration and its operational concept are introduced in this paper. Simulation and experimental results are presented to validate the proposed approach. [ABSTRACT FROM AUTHOR]

Atmospheric-pressure plasma jets (APPJs) are widely used in biomedical treatment, surface modification, and sterilization, among others because of their advantages of simple structure, strong chemical activities, nonthermal effects, and convenient handling. In this paper, a nanosecond-pulse power generator based on Marx circuit is proposed. The apparatus consists of a nanosecond-pulse generator with crowbar switch and a needle-ring structure electrode. The nanosecond-pulse generator is modularly designed with ten stages; MOSFETs are used as the main switch and crowbar switch on each stage. A field-programmable gate array is used to generate two-channel trigger pulse signals to control the turn-on or turn-off of switches. The generator can produce repetitive pulses with output voltages of up to 8 kV, pulsewidth of 100–1000 ns, rise time of less than 30 ns, and pulse repetition frequencies of 1 Hz to 1 kHz. The designed nanosecond-pulse generator and the needle-ring structure electrode are used to produce argon plasma jets into open air, and the experiments show that the nanosecond-pulse generator can sustain stable APPJs. This paper lays a foundation for the further exploration of the biomedical effects of APPJs. [ABSTRACT FROM PUBLISHER]

The U.S. Naval Research Laboratory is developing a rep-rate charger for a 60-kJ capacitor module. The charger is lithium-ion battery powered and must charge up the capacitive load 50 times over a 5-min period with roughly 1 s between each charge cycle. This paper examines some aspects of the design: lithium-ion battery energy storage, hard switched dc–dc converter, high-voltage rectifier, and capacitive load with pulsed power switching. The lithium-ion batteries are arranged in 12, 16-cell, 50 V modules that are connected in series to form a roughly 600 V prime power supply. A hard switched dc–dc converter with full-bridge rectifier is used to charge the capacitor and a pulse forming network is used to discharge the capacitor into the load. This paper will discuss the system design and available test data. [ABSTRACT FROM PUBLISHER]

The role of irreversible electroporation using pulsed electric field is to generate high-voltage (HV) pulses with a predefined magnitude and duration. These HV pulses are applied to the treatment chamber until decontamination of the sample is completed. In this paper, a new topology for HV rectangular pulse generation for water disinfection applications is introduced. The proposed topology has four arms comprised of series-connected half bridge modular multilevel converter cells. The rectangular pulse characteristics can be controlled via the software controller without any physical changes in power topology. The converter is capable of generating both bipolar and monopolar HV pulses with microsecond pulse durations at high a frequency rate with different characteristics. Hence, the proposed topology provides flexibility by software control, along with hardware modularity, scalability, and redundancy. Moreover, a cell’s capacitance is relatively small, which drastically reduces the converter footprint. The adopted charging and discharging process of the cell capacitors in this topology eliminate the need of any voltage measurements or complex control for cell-capacitors voltage balance. Consequently, continuity of converter operation is assured under cell malfunction. In this paper, analysis and cell-capacitor sizing of the proposed topology are detailed. Converter operation is verified using MATLAB/Simulink simulation and scaled experimentation. [ABSTRACT FROM AUTHOR]

In recent years, all solid-state Marx generators have been found more and more extensive applications in industrial, environmental, and biological fields. All solid-state Marx generators have many requirements for their drive circuits, such as good synchrony for driving signals at different stages, fine isolation between control signals and the main circuits, adjustable pulsewidths and frequencies, and good driving abilities. This paper proposes a high-performance drive circuit for a 24-stage Marx generator based on IGBTs. A half-bridge circuit using IR2110 outputs a high-current turning-on drive signal (positive) and a turning-off drive signal (negative) with adjustable dead time. The control drivers are input to the common primary side of 24 nanocrystalline magnetic transformers, which isolate the control circuit and the main circuit. Through gate circuits at the second sides of the magnetic cores, the turning-on drive signal charges 24 gate–emitter capacitors to required voltages and consequently all IGBTs move into on state until the turning-off signal arrives. Similarly, the negative turning-off drive signal charges all gate–emitter capacitors to a negative voltage which ensures all IGBTs stay in the off state. Therefore, the pulsewidth is determined by the phase difference between the turning-on and turning-off drive signals. Equipped with this drive circuit, the 24-stage Marx generator is able to produce stable high voltage pulse with a peak value of −9.6 kV, PRF $0.05\sim 5$ kHz, and different pulsewidths. In this paper, the design details and experimental confirmation of the proposed drive circuit are illustrated. [ABSTRACT FROM AUTHOR]

This paper proposes an active resonance circuit based on multiple series gaps (MSG) with voltage-dividing network and self-charging trigger device. The working principle of active resonance circuit, MSG, and triggering device is described in detail. To determine the optimal parameter setting of MSG, the effects of the voltage frequency, equalizing resistance, and voltage-dividing capacitance on the voltage distribution of MSG are analyzed by simulation. To realize the interrupting process of short fault current and determine the operation requirements of the main devices of precharge direct current (dc) circuit breaker, a simulation model of interrupting short fault current is performed. Furthermore, an experiment of four-series gaps is presented to verify the turn-on characteristic of the MSG and an experiment of artificial current zero is set up to testify the feasibility of the active resonance circuit. The simulation and experimental results show that the active resonance circuit proposed in this paper can generate an artificial zero current and is suitable for precharge dc circuit breaker. [ABSTRACT FROM AUTHOR]

Bipolar junction transistors (BJTs) have been widely studied and used in nanosecond high-voltage pulse generators due to the advantages of fast switching speed and high repetitive frequency. Usually the Marx-type circuit is used to raise the peak value of output pulses. In this paper, a traditional BJT-Marx circuit using charging resistors is analyzed theoretically and experimentally. Based on the results, the structure of a circuit is changed to decrease the isolation voltage across the resistors, and diodes are used to replace charging resistors to block capacitors discharging to resistors. Experimental results showed that the three Marx generators proposed in this paper output pulses with higher voltage amplitude, and the last improved circuit outputs pulses with faster fall times at a higher efficiency. [ABSTRACT FROM AUTHOR]

Nonlinear transmission lines (NLTLs) are nonlinear LC ladder networks that can act as a nonlinear and dispersive medium, thus allowing the generation of soliton bursts. Several papers have been published indicating that NLTLs offer a new option for pulse shaping and RF generation. In this paper, we investigated the response of an NLTL driven by three different pulse shapes: a rectangular, a half sine, and a triangular waveform. The performance of the NLTL was evaluated through time- and frequency-domain analysis of the RF signal sampled at the 29th section of a 30-section capacitive NLTL. The frequency of the generated RF signal is correlated with the shape of the input signal, whereby the output frequency can be adjusted by the amplitude-time characteristics of the pulse at the input of the capacitive NLTL. Higher frequency oscillations, around 30 MHz, were generated by the rectangular wave train due to its shorter rise time. The propagation of solitons along the NLTL is influenced by the input pulse rise time. Namely, the rectangular pulse showed smaller delay time as it had the shortest rise time (less than 10 ns). Maximum efficiency was obtained for the input pulsewidth of 150 ns under a duty cycle of 1/3 for the three pulse shapes (rectangular, half sine, and triangular), and this combination of parameters yielded the highest RF conversion efficiency of the NLTL. The capacitive NLTL showed a higher RF conversion efficiency (16.4%) when driven by the rectangular input signal. [ABSTRACT FROM AUTHOR]

This paper shows how to use modular Marx multilevel converter diode ( \textM^3 CD) modules to apply unipolar or bipolar high-voltage pulses for pulsed power applications. The \textM^3 CD cells allow the assembly of a multilevel converter without needing complex algorithms and parameter measurement to balance the capacitor voltages. This paper also explains how to supply all the modular cells in order to ensure galvanic isolation between control circuits and power circuits. The experimental results for a generator with seven levels, and unipolar and bipolar pulses into resistive, inductive, and capacitive loads are presented. [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]

Theoretically, the energy conversion efficiency of the synchronous induction coil launcher (SICL) can reach 100%, but at present, the test data show that the highest current is only a little higher than 20%, which shows that the efficiency of the coil launcher has a lot of room for improvement. In this paper, three improved schemes are proposed for the topology of the traditional crowbar circuit based on the pulse capacitor to improve the electromechanical energy conversion efficiency of the electromagnetic coil launcher. They are main circuit breaking, crowbar break-off circuit, and crowbar circuit with inductor, respectively. In order to verify the feasibility of the above three methods, a five-stage coil launcher was simulated and analyzed. Then, based on the model, three improved circuits were calculated and analyzed by the finite-element simulation software. The results show that all of the three methods can improve the efficiency of energy conversion to a certain extent. Both the first and second methods have limited effect on increasing efficiency. In addition, they need to add some expensive equipment such as circuit breaker. So, they are not recommended. The third way of increasing an inductor in the crowbar circuit could increase the muzzle velocity and efficiency obviously. The muzzle velocity increased from 30.6 to 35 m/s. The effect of armature capture is reduced which is worthy of recommendation. [ABSTRACT FROM AUTHOR]

In this paper, a modular topology is presented for generating high-voltage pulsed power. The proposed structure consists of Marx-type modules, which are based on the switched-capacitor (SC) concept. This module receives an input voltage and, depending on the requirement of the user, produces an output voltage either equal to the input or twice as much as the input voltage, which shows the flexibility of our model. The capability of the module to produce a doubled output makes it appropriate for applications with low input voltage sources. Also, the topology has the capability of generating combined wide and narrow pulses. The topology was simulated in MATLAB Simulink and a laboratory setup was built to test its operation. The results validate the theoretical basis of the structure. [ABSTRACT FROM AUTHOR]

The power supply for a railgun used as long-range artillery is investigated in this paper. As described in an earlier study, an 8-kg projectile is accelerated to 2500 m/s in order to bring it on a steep ballistic trajectory. To further investigate the electrical behavior of the proposed 25-MJ muzzle energy railgun, simulations with two different power supply chains, each starting with batteries, were performed. The more conventional approach uses a capacitive pulsed power supply (CPPS), the other investigated option is an inductive pulsed power supply (IPPS). An IPPS was designed in detail and set in comparison with a design of a CPPS. Parameters such as size, weight, efficiency, maximum rep-rate, and maximum shots per burst are estimated. Results show that a simple battery–inductor approach promises to be more compact but CPPS would be more energy efficient. Results give valuable support with respect to several design decisions. [ABSTRACT FROM AUTHOR]

Electrical explosion of wires (EEW) can be utilized as an efficient method to prepare nanopowders of metal, metal oxide, metal alloy, and so on, and the behavior of exploding wires varies greatly with different load and circuit parameters. In this paper, the relationship between discharge modes of EEW and load parameters (length and diameter) was studied during the preparation of Al nanopowders via EEW in argon gas. The experimental results showed that with fixed wire length and increasing diameter, the EEW will successively show the feature of current pause, current dwell, current pause again, and finally “being matched”; and for fixed wire diameter, there is a “critical length” of wire which divides the current-dwell mode and the current-pause mode. The critical length as a function of wire diameter peaks between 0.2 and 0.3 mm for the charging voltage of 11.5–20 kV (2.6- $\mu \text{F}$ capacitor); and the specific heat (deposited energy divided by sublimation energy) of wires was approximately 1 at the peaks. [ABSTRACT FROM AUTHOR]

This paper presents some discussions and findings related to the development of the capacitor bank-based pulsed power supply module (PPSM) for an electromagnetic induction coilgun (EIC). Three PPSMs were designed for a three-stage EIC to launch a 21.68-kg projectile at a minimum velocity of 20 m/s. The energy of the PPSM in the first, second, and third stages was 200, 100, and 100 kJ, respectively. Two light-triggered thyristors (LTT) were used as the main switches of the module. The synchronous behaviors of the series LTT, dump circuit, laser diode driver circuit, and protection scheme are analyzed and discussed. The PPSM was built and tested as an EIC system. The simulation results of the PPSM were in agreement with the experimental results. The peak current was about 42 kA at a maximum voltage of 10 kV as in the simulation. The maximum current in the 4-kV launch experiment was 16.47 kA. The velocity of the projectile was more than 25 m/s, which is consistent with the design goal. [ABSTRACT FROM AUTHOR]

This paper proposed the use of a ringer, a self-switched inductive storage system, for applications involving reluctance accelerators, a kind of electromagnetic launcher, and compatible with applications where portability is a requirement. There will be shown three different useful approximations for the analysis of the ringer, employed as a power source for a reluctance accelerator. First, it described the equations governing the que behavior of an ideal unloaded ringer, and then the equations for the ringer with an uncoupled inductive load, and ultimately a Lagrangian model for the ringer as an inductive power source for a reluctance accelerator, capable to make predictions about the currents through the circuits and the exit speed of the projectile for a given firing. The accuracy of the predictions made with the third approximation, the Lagrangian model, was tested experimentally. [ABSTRACT FROM AUTHOR]

In order to realize quick preliminary design for capacitor charge power supply (CCPS), a novel critical analysis method of homopolar inductor alternator (HIA) is proposed in this paper. First, a specific base value system of CCPS is proposed for making the critical analysis method universally applied for different machine and charge parameters. Second, under the equivalent average-value phase model of HIA, a critical curve and a maximum power analysis method based on the curve are proposed. After that, an outline of the preliminary machine design under the critical analysis method is presented. Third, considering the salient rotor structure of HIA, under the equivalent average-value direct- and quadrature-axis (DQ) model of HIA, a critical map as well as its maximum power analysis method is proposed. In the end, for these two types of critical analysis method under different average-value models, each of their advantages and applications are discussed. [ABSTRACT FROM AUTHOR]

This paper is devoted to the design, implementation, and test of a low cost, modular, and reliable pulsed high-voltage (HV) converter (dc chopper). The distinct characteristics of the present prototype refer to: adjustable voltage amplitude up to 7 kV, amplitude drop less than 4‰ for $2 \times 10$ A output peak current at 5 kHz, adjustable pulse frequency up to 5 kHz, adjustable duty cycle between 1% and 10%, rising/falling time around 100 ns, and jitter about 10 ns. In principle, 1-kV modules based on a fast MOSFET each are combined in series to form a completely modular push–pull switch configuration. Contrary to sophisticated optical fiber-based insulation techniques, the driving low-voltage stage of the power supply is magnetically coupled to the HV stage. The low-voltage stage defines and schedules the HV pulses by means of a microcontroller. The 7 kV is equally distributed along MOSFETs due to balancing networks of passive components. Zener diodes in parallel with MOSFETs provide sufficient protection against overvoltages. The power supply has been successfully tested on dielectric-barrier discharge-based plasmas which have nowadays continuous technological interest. [ABSTRACT FROM AUTHOR]

In this paper, we designed an active coupling trigger circuit and an active surge protection gap (ASPG). The surge protection level of the passive SPG is improved, and the operating time of the passive SPG is shortened. The equivalent circuits for the coupling trigger circuit were developed. Then, we analyzed the component transient voltage of the active coupling trigger circuit with the combination wave injected. We obtained the numerical relationship between the coupling trigger current and the current flowing through the ASPG. In addition, the timing relationship between the component voltage and the current was acquired. To verify the analysis results, we established the combination wave generator and conducted an experiment. In the experiment, we observed that the trigger circuit operating time and the ASPG impulse breakdown voltage changed with the capacitor charging voltage of the combination wave generator. Furthermore, we discovered the change laws. The results also show that the operating time and impulse breakdown voltage of the ASPG are both smaller than the passive SPG. These results provide an important theoretical and experimental basis for the further study and structural optimization of the ASPG. [ABSTRACT FROM AUTHOR]

This paper is aimed at finding the effect of varying inductive energy storage systems’ (IESSs) inductance on resistance of an electrically exploded conductor-based opening switch and profile of current transferred into load, which has not yet been fully understood. Based on experimental results obtained, it is observed that when the inductance of IESS is varied, the magnitude of load current changes so as to conform to the magnetic flux conservation law but its rise time remains unchanged. Resistance of the opening switch and energy deposited in it has been estimated using recorded voltage and current waveforms. It has been found that with increasing inductance of IESS, the resistance of switch increases, whereas energy deposited in it decreases. Using these estimated values of energy, a possible explanation of observed behavior in resistance is presented. Effect of a mismatch between the inductance of IESS and load is seen to only affect the energy transfer efficiency or magnitude of load current but not its rise time emphasizing the novel finding that for a given load, the rise time of load current is independent of the inductance of IESS. [ABSTRACT FROM AUTHOR]

Previous research has shown the applicability of nonlinear transmission lines (NLTLs) in high speed and wide bandwidth systems. These applications involve techniques for forming and sharpening a short electrical pulse to achieve pulse compressors, frequency multipliers, phase shifters, and, in addition, radio frequency (RF) generation, holding, in this case, a great potential for replacing vacuum electron tubes with a low cost and fully solid-state technology. Based on the analysis of relevant experimental results of different types of NLTLs reported in the literature, this paper presents an investigation about the correlation between the performance limits of NLTLs and specific characteristics of the materials used in their construction, concluding that there is a pressing demand for the development of high-performance dielectric and magnetic materials with special characteristics such as highly nonlinear behavior, low losses at microwave frequencies, and thermal stability that would allow for an improvement in the performance of NLTLs, enabling their operation at higher frequencies and with better electrical-to-RF conversion efficiency. The achievement of a stable behavior over a broader operating temperature range would allow the application of NLTLs in military and aerospace devices. [ABSTRACT FROM AUTHOR]

In this paper, a high-voltage unipolar pulse power generator is introduced for electroporation applications. Operating principle of the proposed structure is based on the buck–boost (BB) converter. The generator is comprised of parallel modules connected to the converter through an SCR and is supplied by a low-voltage dc source. Each module consists of an insulated gate bipolar transistor (IGBT), two diodes, and a capacitor. In fact, the proposed topology is a combination of the Marx generator and BB (MG-BB) converter. In comparison with other modular MG-BB structures, the proposed topology achieves interesting advantages including simpler structure, reduction of IGBTs voltage rating, and reducing number of components (inductors and switches). In order to clarify the features of the proposed structure, it has been compared with other unipolar MGs considering different aspects including the number of circuit components, number of required input supplies, amplitude of the output pulse, and the maximum voltage across switches and diodes. To validate the effectiveness of the structure, simulation and experimental results are presented. The results confirm that the proposed topology is capable of generating unipolar pulses with desirable amplitude and repetition frequency using a low-voltage dc supply. [ABSTRACT FROM AUTHOR]

A pulsed electromagnetic inductive valve has been developed to achieve correct initial deposition of the propellant gas puff for the planar pulsed inductive plasma thruster. This paper aims to describe the method for modeling the valve. The most significant physical effects involved in the valve operation process are described by the electrical model, the magnetic model, the mechanical model, and the pneumatic model. These physical models are then linked together based on the couplings between them to form a complete multiphysics coupling model. In order to validate the proposed model, simulations and experiments are implemented for the prototype valve at different operating conditions. Response characteristics and throughput characteristics predicted by the model agree well with experimental data. The results demonstrate that the proposed model can be successfully applied to accurately capture the main performance of the valve. The principle of the analysis procedure is applicable to other electromagnetic valves of this type. [ABSTRACT FROM AUTHOR]