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This paper describes a high-frequency pulsed-power generator for various industrial applications such as water treatment, food and medical apparatus for sterilization, or polluted gas treatment. The system is made of silicon-controlled rectifier as a main trigger switch, capacitors, two-stage magnetic pulse compression stages, and a linear transformer to generate a maximum of 120-kV, 5-kA pulse. The parameters obtained through the development are: output voltage: 120 kV (maximum), pulse repetition ration: 300 pulse per second, pulsewidth: 0.25~\mu \texts , and mean power: 30 kW. The designed pulsed-power generator is confirmed to be used effectively for many high-voltage pulsed-power applications related to environmental industry by simulation and experiments. [ABSTRACT FROM AUTHOR]

This paper presents the design and experimental results of the 36-kW pulsed-power supply for the xenon flash lamp. The continuous conduction mode series-parallel resonant converter is modified. This means that not only the few hundred kilohertz of high switching frequency is introduced to replace the resonant inductor with the leakage inductor of transformer but also the high output current is accomplished by using three-phase delta-connected transformers. In addition, the snubber capacitor of the inverter switches and the power factor correction module is both omitted in the compact structure. Although these main components have changed, the efficiency and power factor of the rated dummy load reach 96% and 0.96%, respectively. Within 36-kW average power, the proposed pulsed-power supply can generate as versatile combination of output pulse. For example, it can generate 20-ms pulse with 1-Hz repetition rate or generate 1-ms pulse with 20-Hz repetition rate. The used insulated gate bipolar transistor is protected from the turn-OFF peak voltage by the snubber circuit, and the effect of the snubber circuit is shown at the actual load condition. [ABSTRACT FROM PUBLISHER]

This paper presents generalized dynamic models for Marx derived multilevel half-bridge bipolar modulators. This high-voltage topology uses modular Marx multilevel converter diode ( \textM^\mathrm 3 CD) cells to generate positive and negative (bipolar) pulses or unipolar (positive or negative voltage pulses). The developed models are tested in transient studies of pulse voltages and currents in the load. Simulation and experimental results are presented and compared. [ABSTRACT FROM PUBLISHER]

A novel circuit with the better performance for the inductive pulsed power supplies in the electromagnetic launch system is proposed in this paper, namely, the meat grinder with capacitive pulse forming unit (CPFU). Its working process is qualitatively analyzed stage by stage. Its practical feasibility is verified through a 7.5-kJ experiment. From the perspectives of circuit structure and working principle, this circuit can be regarded as the combination of a meat grinder and a CPFU. Compared with its preceding circuits, this circuit possesses following advantages: 1) the self-recovery of the capacitor precharged voltage can easily be achieved, which is conducive to continuous operations of the whole circuit and 2) the waveforms of the inductor currents contain no capacitive components, which can promote the energy storage density of the inductors. [ABSTRACT FROM PUBLISHER]

The opening switch is one of the critical technologies in the development of inductive pulsed-power supply. The power requirement is very high when the opening switch is desired to commutate a large current. This paper presents a zero-current opening circuit for inductive pulsed-power supply based on a high-temperature superconducting pulsed-power transformer. First, there are two types of current flowing through the opening switch, one comes from the secondary side of the pulse transformer, and the other one comes from superconducting energy storage inductance. The orientation of the two current is opposite. Then, when the current flowing through the opening switch closes to zero, the switch is opened and this restrains the over-voltage pulse of the opening switch. The simulation results indicate that this zero-current opening circuit is feasible and has potential applications for high-energy systems in the future electromagnetic launcher. [ABSTRACT FROM PUBLISHER]

High-voltage (HV) pulses are used in pulsed electric field (PEF) applications to provide an effective electroporation process, a process in which harmful microorganisms are disinfected when subjected to a PEF. Depending on the PEF application, different HV pulse specifications are required such as the pulse-waveform shape, the voltage magnitude, the pulse duration, and the pulse repetition rate. In this paper, a generic pulse-waveform generator (GPG) is proposed, and the GPG topology is based on half-bridge modular multilevel converter (HB-MMC) cells. The GPG topology is formed of four identical arms of series-connected HB-MMC cells forming an H-bridge. Unlike the conventional HB-MMC-based converters in HVdc transmission, the GPG load power flow is not continuous which leads to smaller size cell capacitors utilization; hence, smaller footprint of the GPG is achieved. The GPG topology flexibility allows the controller software to generate a basic multilevel waveform which can be manipulated to generate the commonly used PEF pulse waveforms. Therefore, the proposed topology offers modularity, redundancy, and scalability. The viability of the proposed GPG converter is validated by MATLAB/Simulink simulation and experimentation. [ABSTRACT FROM PUBLISHER]

A portable dc power supply based on electric double-layer capacitor (EDLC) bank was established for high-power applications. EDLC bank needs a dc–dc converter to maintain a constant output voltage and current. Especially, a low-impedance load makes the voltage of capacitors discharge faster, and their discharging time is determined by RC time constant. The proposed system is designed as a fundamental concept, and deals with some issues occurring in a large-scale system. Also, this paper provides detailed information and consideration for a real establishment. Last, we performed a full-scale experiment using basic techniques. [ABSTRACT FROM PUBLISHER]

Multipole field electromagnetic launcher (MFEL) is a new type of coilgun that can produce larger radial magnetic field compared to the axial magnetic field, the axial acceleration force of coilgun mainly come from radial magnetic field. Because of the similarity of the magnetic fields between inner and outer regions of MFEL, this paper proposed a double-armature MFEL. One armature coaxial with the drive coil placed inside of MFEL; the other armature coaxial with the drive coil placed outside of MFEL. A single-stage double-armature MFEL was studied by simulation and experimental methods. The simulation results indicated that the muzzle velocity of the double-armature launch is similar to that of the single-armature launch, and the efficiency of double-armature MFEL is obviously larger than that of single armature. To verify the conceptual feasibility, a small-size single-stage double-armature capacitor-driven MFEL was built and tested. The inner small armature weighs 63.13 g, the outer big armature weighs 88.38 g. The experimental results on single-armature launch show good consistency with the simulation results, but there is a little gap between the experimental results on double-armature launch and the simulation results. The causes of the existing differences are considered to be mainly from the consistency difference between the six driving coils and the mutual influence between the inner and outer armatures. [ABSTRACT FROM PUBLISHER]

A 200 kJ pulsed power system (PPS) has been built up to drive pulsed plasma devices. This PPS consists of two 100 kJ capacitor bank modules, each comprising of five capacitors of each 178~\mu \textF , a discharge switch, and a pulse-shaping unit. When both the banks are charged simultaneously to −15 kV using full charging technique, it delivers a peak current 100 kA at the load (damping resistor and pulse-shaping inductor). Later on, a plasma system will be attached at the load which will also have an inductive and resistive effect. A fiber-optic triggering unit controls both the modules and there exists a flexibility of sometimes operating a single module only, besides there are provisions for further up gradation of the PPS to a targeted 600 kJ. Prior to this development, PSpice simulation was carried out to estimate the parameters of the circuit components to achieve the required wave pulse with precision. Using these parameters, a design of the PPS was made keeping into account about the critical issues involved and the ratings of the components, some of which were fabricated in house. This paper basically includes the criticality surrounding the operation of a high-energy long-pulse PPS under negative operating voltage. [ABSTRACT FROM AUTHOR]

Temperature field simulation for self-healing power capacitor makes sense to the capacitor optimization and improvement of capacitor’s rated voltage and capacity. On the basis of reasonable simplifications and assumptions for capacitor structure, a 3-D temperature field numerical simulation model for a self-healing power capacitor is formulated in Fluent 15.0. The ambient temperature is set to 55 °C, and the applied voltage is ac 400 V. The temperature distributions of the shell and core of the self-healing capacitor are obtained. The results reveal that the temperature of the core is 2 °C–3 °C higher than that of the shell. The highest temperature of the shell locates on the large side surface, and the temperature of the large side surface is higher than that of the small side surface. To validate the above simulation, a self-healing capacitor is manufactured and thermal resistance sensors are used to measure the temperature in the thermal stability test. The simulation is validated by the experiment. Finally, the influences of the ambient temperature and applied voltage on the temperature rise are investigated. This paper can be taken a reference to the self-healing capacitor operation, maintenance, and even the optimization of its internal structure and material. [ABSTRACT FROM PUBLISHER]

Augmented railgun as advanced mass accelerators, which are using an additional magnetic field to support the launching process. In conventional electromagnetic accelerators, the electrical current through the rails and the armature have to be very large to achieve a sufficiently high electromagnetic force that accelerates the projectile. The electrical energy for the launching process is supplied by a pulsed power supply. The 9-kJ pulsed power units have been built for the 270kJ electromagnetic launchers. The 270-kJ powered power supply can fine-adjust the current and reduce the voltage of the thyristor switch and capacitor demands to maximize the economic benefit. The 9-kJ pulsed power units have been built for the 270-kJ electromagnetic launchers. In this paper, the two-turn augmented railgun with a 15 mm $\times23$ mm bore and 2.5-m-long rails were designed, which enable to accelerate the 15-g projectile to velocities above 2.5 km/s. It was driven by the 270-kJ pulsed power system. The maximum efficiency of whole electromagnetic launching system can reach 20%. [ABSTRACT FROM PUBLISHER]

Electrical parameter such as charging voltage and time series of discharge in repetition-frequency pulse power supply (RFPPS) can be adjusted. In order to obtain the accuracy of launch time and enough muzzle energy, constant current charging technology is taken, which can make RFPPS charge linear and the discharge time same in each discharge cycle. In this paper, the influence factors of accuracy are analyzed. It is proposed to control the accuracy of the charging time by means of the closed-loop feedback of the average charging current. A simulation and experiment of RFPPS test system are established. The results of simulation and experiment show that the charging time is proportional to the charging voltage after pulse-frequency modulation. The launch time can be determined by the charging voltage. Through this way, incoming target will be intercepted if the interception distance and the launching velocity are measured and calculated accurately. [ABSTRACT FROM PUBLISHER]

In the real world application of railguns, the launch efficiency is one of the most important parameters. This efficiency directly relates to the capacity of the electrical energy storage that is needed for the launch. In this paper, the rail/armature contact behavior for two different armature technologies was compared. To this end, experiments using aluminum c-shaped armature and copper brush armature type projectiles were performed under same initial conditions. The c-shaped armature type showed a superior behavior with respect to electrical contact to the rails and in acceleration. A 300-g projectile with a c-shaped armature reached a velocity of 3100 m/s and an overall launch efficiency including the power supply of 41%. This is to be compared with 2500 m/s and 23% for the launching of a projectile using a brush armature. [ABSTRACT FROM PUBLISHER]

The meat grinder is a basic circuit for inductive pulsed-power supply (IPPS). Based on meat grinder, the Institute of Advanced Technology proposed a circuit called the slow transfer of energy through capacitive hybrid (STRETCH) meat grinder, in which an Integrated Gate Commutated Thyristors (IGCT) is selected as the main switch. Tsinghua University proposed the STRETCH meat grinder with inverse current commutation with semiconductor devices (ICCOS) in which the main switch is replaced by a thyristor and the ICCOS subcircuit is introduced to turn off the main switch. To reduce the opening switch voltage and increase the current turning-off capacity for IPPS, this paper presents a novel circuit topology named the meat grinder with self-charged capacitor and thyristors (SECTs). The key idea of the SECT topology is to turn off the primary current by the energy transfer capacitor, which is precharged. The meat grinder with SECT has larger capacity than the STRETCH meat grinder because it replaces the IGCT with a thyristor and is simpler than the STRETCH meat grinder with ICCOS because it only needs one capacitor. The suggested circuit is more suitable for IPPS module with high energy density. Simulation and experiment have been carried out to validate the circuit. [ABSTRACT FROM PUBLISHER]

Electromagnetic launching mass driver system (projectile) has been examined and evaluated as an eligible alternative to the chemical propulsion systems, in space transportation. The projectile has been arranged to reach to its orbital speed at delivered altitude, with an energy transferred externally to a projectile all the flyway through the electromagnetic launcher. The multistage electromagnetic launcher structure contains the capacitors for storing energy and transfers this energy through a switching inductor to a mass driver. The mass driver is synchronously being energized by a voltage through an oscillating coil-capacitor circuit. This paper presents dependence and optimization of design and performance parameters of coilgun equations. Cost estimations of electromagnetic launching system are also calculated in energy per unit mass. [ABSTRACT FROM PUBLISHER]

Magnetic pulse compression (MPC) system has been widely used over a few decades as a technique for producing short duration, high peak power pulses reliably. Novel MPC system which do not contain external demagnetization circuits, have broadened the appliance of MPC systems, in which circuit in each level of storage energy capacitors is composed of two capacitors in series, and the two-capacitance combination is connected to the output of previous stage, so that not only the pulse is compressed but also the voltage is doubled as well. In this paper, a 20-kHz high repetition-rate pulse generator with adjustable output amplitude based on Novel MPC system is presented. The pulse generator makes use of commercially available insulated gate bipolar transistor (IGBT), switching a capacitor bank into a ferrite transformer together with a voltage doubling circuit. The capacitor bank is charged to 530 V by a three-phase rectifier, also switched by a commercial diode. The amplitude of the output voltage of the pulse generator is controlled by the amplitude of the gate voltage of the IGBTs. Pulses with a width of 70 ns can be generated with repetition rates up to 20 kHz in burst. The amplitude can be controlled from 5 to 40 kV into a $500~\Omega $ resistive load. [ABSTRACT FROM AUTHOR]

Armature is very important for a synchronous induction coil launcher which can transform the electric energy to kinetic energy and push the load forward. The structure of the armature will influence the kinetic energy conversion efficiency directly. This paper analyzes the armature structure of a capacitor-driven synchronous induction coil launcher. Length and thickness of the armature are analyzed that how these parameters influence the maximum velocity and system efficiency of the launcher. Current filaments model is used to calculate the motion characteristics of a tubular linear induction motors, which is verified by an experiment and finite-element code. Genetic algorithm optimizer is used to calculate the best trigger times of the coils and the maximum velocity under the conditions of different length and thickness of the armature. It is shown that when the armature mass is fixed, length and thickness of the armature will greatly increase the velocity of the armature. The best length of the armature should be almost 2–2.5 times the length of the coil. The best thickness of the armature could be estimated by skin depth. [ABSTRACT FROM PUBLISHER]

In the field of electromagnetic launch or other military research, the requirements for the power density of high-voltage capacitor charging power supply (CCPS) are increasing. The design of the cooling system becomes more difficult, especially in the intermittent operation mode, when the power supply exists transient heating process. As the main heating element of CCPS, the inverter unit is the key factor to influence the power density. In this paper, the main factors that influence the temperature rise of the device are analyzed, including the material and size of the heat sink. The rules between the above factors and the transient temperature rise are analyzed by Matlab simulation software. Then, the architecture model of inverter unit is established through ICEPAK software for simulation, which proves the accuracy of the regular. A basis for designing system level power supplies working in intermittent operating mode is provided through the transient thermal design of inverter unit’D The accuracy of the rule is verified through some load short circuit experiments with a 30-kW/6 kV charging power supply. [ABSTRACT FROM PUBLISHER]

The major strengths of inductors in energy density and power density make an inductive pulsed power supply (IPPS) a promising option for pulsed power supplies in an electromagnetic launch system. Among the circuits for an IPPS, the capacitor-aided meat grinder circuits constitute an important branch. An analytical method for the working processes of these circuits is proposed in this paper. The core of this method is the decoupling of a high-order circuit into the superposition of a resistor–inductor first-order equivalent subcircuit and a resistor–inductor–capacitor second-order equivalent subcircuit. The validity and accuracy of this method have been verified through comparison with a numerical simulation. The results show that this method possesses both satisfactory accuracy and excellent computational speed. With the same circuit parameters and time step, the time cost of this method is three orders of magnitudes lower than the time cost of a numerical simulation. Moreover, this method contributes to more intuitive understanding and more essential insight into the working principles of the capacitor-aided meat grinder circuits. [ABSTRACT FROM PUBLISHER]

Brushless doubly-fed alternator (BDFA) has good application prospects in pulsed alternator. It works through the rotor’s pole pairs transformation function to get excitation indirectly. Since there are no brush and slip ring, BDFA is expected to have high reliability and long service life. This paper studies on the excitation control of BDFA in pulse capacitor charge power supply system. A mathematic model of BDFA is established. The power angle characteristic of BDFA and flux changing condition during discharging process is analyzed with this model. Based on the analysis, a novel excitation control theory is proposed. Simulation results are presented to illustrate the performance of this control strategy. [ABSTRACT FROM PUBLISHER]

With inherent strengths in energy density and power density, the inductive pulsed power supplies (IPPS) have become an attractive option for the power supplies in electromagnetic launch systems. The meat grinder circuits, including the slow transfer of energy through capacitive hybrid (STRETCH) meat grinder circuit, the STRETCH meat grinder with inverse current commutation with semiconductor devices circuit, and the meat grinder with self-charged capacitor and thyristors circuit, constitute one major branch among the IPPS circuits. This paper summarizes the fundamental research work and contributions of the meat grinder circuits from the perspectives of circuit improvements, performance analysis, inductor design, module collaboration, and efficiency promotion. The future directions of single IPPS module are higher energy level, larger energy density, and higher efficiency. [ABSTRACT FROM PUBLISHER]

As power supplies, compulsators are popular choices for high-end railgun power supplies. In order to increase power and energy density, air-core compulsators are proposed by using composite materials instead of traditional iron-core compulsators. Due to the absence of ferromagnetic material, the flux density in the air-core compulsator can reach to 4–6 T instantaneously, which is much higher than the saturation field strength in traditional iron-core machines. Therefore, self-excitation topology is essential for the air-core compulsator to obtain up to 100-kA field current. This paper carried out research on the key parameters of self-excitation efficiency first, and then focus on the large magnetic energy remained in the inductive field winding after one shot, an implementation scheme and control strategy of energy recovery of air-core compulsator was proposed and analyzed. By controlling the field rectifier working at active inverter state after one discharge process, the magnetic energy stored in the field winding can be converted to rotor kinetic energy again. The simulation results indicate that the energy recovery efficiency can reach to 70% for a reference air-core compulsator. The continuous discharge number of times increased from 3 to 4 during one kinetic energy charging, which means that the delivered energy density increases 33.3%. [ABSTRACT FROM PUBLISHER]

One of the main reasons of metal film capacitors failure in pulse modes is a degradation of contacts between film metallization and solid electrodes—contact edges. This paper presents the results of experimental investigations of modeled contact edges behavior under current pulses of varying amplitude, duration, and quantity. It was found that the contact edge degradation is caused only by metallization destruction and independent on metal of the solid electrodes (“shoopage”). Depending on pulse parameters and dissipated energy in the contact edge, the contact erosion rate is in the range of (0.4– 2.7) \times 10^-3 g/J. Current pulse polarity effect on contact edge degradation was found: mean time to failure (MTTF) of the contact edge depends on its polarity, i.e., on the direction of the current flow through the contact during charge or discharge of capacitor. For different contacts polarities the difference between MTTFs reaches 20%–60% depending on pulse parameters. Based on these facts, one makes a supposition that the timely changing of the capacitor’s terminals polarity can lead to the increasing of capacitor lifetime. [ABSTRACT FROM PUBLISHER]

An inductive coil gun is a solenoid surrounding a cylindrical metallic armature (the projectile), both electromagnetically coupled. One or more capacitors discharge a stored voltage quickly through the coil, configuring a kind of RLC circuit, with the pulse-shaped current generating a magnetic field inside the coil that accelerates the projectile. Once the projectile crosses an equilibrium point inside the coil, the existing magnetic field pulls the armature back, therefore reducing the final muzzle velocity and decreasing the efficiency—defined as the ratio between the available capacitor electrostatic versus the slug kinetic energies. This paper describes a system that monitors the armature position inside the coil, with a laser beam, and automatically cuts the current when the projectile reaches the equilibrium point. The system, named current switch circuit, enables higher velocities using the same set of coilgun and projectiles, providing a higher efficiency. [ABSTRACT FROM PUBLISHER]

This paper presents a novel technique for the voltage droop compensation of long pulses in solid-state bipolar high-voltage Marx generators. Considering the modularity of Marx generators the compensation consists in adding one extra stage to perform as a pulsewidth modulation circuit. This stage voltage is added to the output positive or negative pulses, and an output LfCf filter is included to smooth the voltage pulse waveform. A five-stage laboratory prototype of this circuit has been assembled using 1200-V Insulated Gate Bipolar Transistors and diodes with 1000-V dc input voltage. The circuit was operated at 50-Hz bipolar pulse rate, giving 4-kV bipolar pulses, into a resistive load, with 100- \mu \texts pulsewidth and 9.5-ms relaxation time. The circuit was able to compensate 10% of bipolar pulse voltage droop. [ABSTRACT FROM PUBLISHER]

In this paper, the effect of external magnetic field loaded at the initial period of inertial stretching stage on a jet produced by Ø56-mm shaped charge is evaluated through the depth-of-penetration (DOP) test method. Experimental results are compared with the results obtained under the field loaded at the later inertial stretching stage. A standoff of 650 mm is used in the experiments, in which the shaped charge jet can undergo formation, elongation, breakup, rotation, and drift. The initial energy is provided by a capacitor bank, which is loaded on the solenoid to generate a magnetic field used for coupling with the jet. The external magnetic field loaded at the initial period of inertial stretching stage can enhance the stability of the jet and increase its DOP. The penetration capability of the jet in the above-mentioned condition is increased by 77.4%. [ABSTRACT FROM AUTHOR]

The amount of stored energy is an important issue in the low-droop and high-precision pulse generation. Pulse forming network (PFN) simulating an open-ended transmission line seems to be useful due to its minimum stored energy. The drawbacks of the PFN include low-output pulse quality and constant pulsewidth, which limit their applications. Another limitation of generating rectangular pulses using PFN is that half of the charged voltage appears in the output when delivering the entire stored energy to the matched load. This paper proposes a structure of PFN-based pulse generator that overcomes the above-mentioned limitations. For continuous pulsewidth adjustment, a lossless scheme is presented. By increasing the ratio of the load magnitude to the characteristic impedance, the amplitude of the output pulse voltage would be approximately equal to that of the charged voltage. Therefore, the semiconductor switches can be utilized in the PFN pulse generator easily. In addition, the pulse quality is enhanced and faster rising time is obtained in comparison with the conventional PFNs. In this proposal, the stored energy quantity is limited to three times the energy needed for the output pulse in the case of RL=10Z0 . To verify the proposed structure, a prototype is simulated using PSPICE software, and the experimental results are presented. [ABSTRACT FROM AUTHOR]

Electromagnetic railguns (EMRs) launch projectiles by the systematic triggering of current pulse forming units (PFUs), which release stored capacitor energy. Past work has focused on maximizing projectile velocity at the muzzle for given PFU capacitor charge voltages, which maximizes efficiency. However, operators in naval applications need to be able to select the muzzle velocity for a projectile to achieve a desired ballistic path. Thus, there is a demand to maximize efficiency for a given muzzle velocity. As such, this paper investigates maximizing the efficiency of transferring the stored PFU capacitor electrical energy to projectile kinetic energy while minimizing the current value when the projectile exits the rails to reduce damage to them from arcing. This is accomplished by optimizing the choice of the initial capacitor voltage in each PFU and the trigger timing subject to an electrical-mechanical dynamic model of the EMR and projectile and any additional scenario constraints (described shortly). This optimization is solved using numerical programming in the context of a relaxation with the initial capacitor voltages and triggering times as the only explicit variables to the optimizer; additional needed values are obtained from a differential algebraic equation solver. The optimization is successfully demonstrated for three scenarios: operation for a projectile mass and muzzle velocity associated with published operating parameters, operation for several projectile mass-muzzle velocity pairs with both equal and distinct initial capacitor voltages, and operation for several projectile mass-muzzle velocity pairs with a load current bound and equal initial capacitor voltages. Results show improved efficiency in comparison to the use of the published parameters, the independence of efficiency from projectile mass when there is no current bound, virtually identical results for equal and distinct initial capacitor voltages, and decreased efficiency with a current bound. [ABSTRACT FROM PUBLISHER]

In the case of back-to-back capacitor banks switching, the inrush current arcs can locally melt the contact surfaces of vacuum interrupters (VIs) during the prestrike process. The contact materials significantly influence the behaviours of the inrush current prestrike arcs. The objective of this paper is to determine the influence of contact materials on prestrike arc behaviours of VIs during capacitive making processes. Six identical 12-kV VIs were used in the experiment after the proposed conditioning. The contact diameter of the VIs was 48 mm, and the insulating envelope was transparent. There were no metal vapour shields inside the VIs to enable the observation of the prestrike arcs. Two different contact materials (CuCr50/50 and CuW10/90) were used in the experiment. Test inrush currents were set to 5-, 10-, and 20-kA peak values, respectively. The inrush current arc features were recorded by a high-speed charge-coupled device video camera. It is discovered that the contact materials have a significant influence on the prestrike gaps. Moreover, the prestrike arcs in VIs with the CuW10/90 contact material tend to be more diffuse than those in VIs with the CuCr50/50 contact material. The results indicate the impact of different contact materials on the prestrike arc behaviours and reveal the contact erosion patterns for different materials. [ABSTRACT FROM PUBLISHER]

In recent years, nonlinear transmission lines (NLTLs) have been investigated for high-power radio frequency generation. High-power waves produced using NLTLs can be applied in mobile defense platforms and satellite communications as they can reach tens of MW of peak power. Their principle of operations is based on the nonlinearity of inductive and/or capacitive lumped elements used in such lines. In this paper, an NLTL using commercial ceramic capacitors as nonlinear elements and linear inductors was simulated and built. Experimental and simulated results show good agreement, validating the model of ceramic capacitors. The frequency obtained from soliton generation at the output of the line was about 4 MHz with peak power of the order of 8 kW. [ABSTRACT FROM PUBLISHER]

This paper presents a power electronics converter to generate bipolar high-voltage pulses using low-voltage dc source. Converter is designed based on charging of different capacitors by a predetermined switching pattern and their discharging on the load for pulsed power applications. Low number of power electronics devices and bulky transformer elimination are main advantages of the proposed converter. According to new findings, bipolar high-voltage pulses may lead to higher efficiency in many applications, such as food sterilization industry. The proposed pulse generator generates bipolar controllable pulses with a modular circuit structure based on a capacitor-switched network. Experimental results are presented to verify the analysis. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of the axial magnetic field (AMF) arc control on voltage distribution (VD) of double-break vacuum circuit breakers (VCBs) in order to gain balanced VD, and thus enhance the breaking capacity. The interaction of vacuum arc plasma, postarc current (PAC), and AMF is discussed. We conduct the breaking test of double-break VCBs with externally applied AMF of a different pulsewidth, magnitude, and a different moment. The PAC, postarc charge, and the VD are measured to analyze the relationship between the AMF arc control and the VD. The optimal AMF arc control and the relationship between the AMF magnitude and the unbalanced voltage ratio are gained when the grading capacitors were 400 pF. The experimental test showed that the proper AMF arc control can improve the unbalanced VD. The mechanism is that the proper AMF arc control can make the postarc charge small and stable, so the unbalanced postarc charge, which caused the unbalanced VD is limited. [ABSTRACT FROM AUTHOR]

This paper outlines the design and implementation of a solid-state high-voltage, high-frequency pulse generator used to drive capacitive loads and particularly, nonequilibrium plasmas at atmospheric pressure. The generator is capable of producing open circuit pulses of 0–12 kV with a 300 ns duration (full-width at half-maximum) at a repetition frequency of 0–25 kHz. The working principles of the generator are presented, along with its electrical diagnostics to illustrate its operation with capacitive loads. The generator was applied to a pin-to-plane electrode configuration to generate a diffuse nonequilibrium plasma discharge with peak voltage of 12 kV. Energy deposition and average power required to drive the discharges in open air at 25 kHz were calculated to be 112 \mu \textJ /pulse and 2.80 W. The generator was also applied to lean, stagnation-plate stabilized V-shaped flames to increase their blowoff velocity. A 28%–51% increase of the blowoff velocity is observed using a discharge with the peak voltage of 6.2 kV, and the repetition rate of 25 kHz. [ABSTRACT FROM AUTHOR]

The slow transfer of energy through capacitive hybrid (STRETCH) meat grinder circuit is a widely used topology in inductive pulse power supply. Therefore, it is important to understand the relationship between the STRETCH meat grinder performances and the inductor parameters when improving the system performance and designing the inductor. From the perspective of inductor designing, this paper uses four indicators to present the STRETCH meat grinder performances, i.e., the charging current, the current amplification, the inductor energy density, and the discharge efficiency, and uses two indicators to present the inductor parameters, i.e., the total inductance and the ratio of the inductance L1 to L2 . First, the meanings of the indicators are explained or defined. Second, simulations and experiments are carried out, respectively, to analyze the trends of the four performance indicators along with the changes of two parameters indicators. Finally, both simulation and experiment results show that the increase of the total inductance leads to the decrease of the charging current and the discharge efficiency; moreover, the increase of the ratio of the inductor L1 to L2 leads to the increase of the current amplification and the discharge efficiency, but causes the decrease of the inductor energy density. [ABSTRACT FROM AUTHOR]

The high-speed electromagnetic (EM) rail launcher has a wide range of applications. An inductive shunt device is usually paralleled with the rails of the launcher as an approach to limit the muzzle arc by transferring the extremely high armature current. The shunt parameters will significantly influence the rail current, armature velocity, and device stress conditions, which also makes the physical process more complicated. In this paper, a circuit-EM-mechanical coupled simulation model is developed to analyze the launching process. Based on this model, the influences of shunt impedance, armature resistance, and capacitor energy are investigated numerically. The EM force, stress conditions, and deformation of the shunt are studied as well. In addition, some launcher design suggestions are given according to the conclusion. [ABSTRACT FROM AUTHOR]

The series configuration of fast semiconductor switches seems to be the key component in the high-voltage and fast rising time pulse generation. In this approach, two important issues must be considered. The first is to provide a safe operating condition for the switches in transient intervals. The second is to design a gate drive system with the capability of driving a large number of discrete devices simultaneously. The aim of this paper is to obviate these two requirements. First, different factors affecting the unbalanced voltage sharing between the series switches are discussed. In this investigation, the switch-to-ground parasitic capacitance effect has been recognized as the major effect on the unbalanced voltage sharing in the transient interval. Two schemes for abating this effect are proposed. To solve the unbalanced voltage distribution, the structure with a snubber circuit in the clamp mode operation is suggested. This scheme can be used for any number of switches without destructively affecting their behavior. In addition, the output pulse with a fast rising time could be obtained by the proposed gate drive system. In order to evaluate the operation of the proposed structure, a stacked switch with the voltage capability of 36 kV is tested experimentally. The characteristics of the obtained pulse are the fast rising time (69.5 ns) with the dV/dt of 460 kv/ \mu \texts and the wide range of the pulsewidth adjusting to 0.5–15 \mu \texts . In addition, the voltage variance of the switches level in the series structure is about 10%. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of energy partition among various physical processes during the formation of an electrical arc. The experimental work was conducted to accurately determine the energy delivered into the discharge. The transient voltage and current waveforms have been measured. An analytical model was developed that allows estimation of energy partition in the discharge to be performed in order to evaluate risks associated with different energy components: thermal, kinetic acoustic, and light. Approximately 60% of the electrical energy is converted into mechanical work, subsequently contributing to the pressure rise. The results obtained will help in studies of safety considerations regarding hazards associated with plasma discharges in transient faults/sparks and during the onset of arcing faults (flash and blast hazards). [ABSTRACT FROM AUTHOR]

The field-reversed configuration heating experiment (FRCHX) was designed to form closed-field-line magnetized target plasmas for magnetoinertial fusion and other high energy density plasma research. These plasmas are in a field-reversed configuration and are formed via a reversed-field theta pinch on an already magnetized background plasma. To extend the duration and temporal uniformity of the pinch, the capacitor bank driving the reversed-field discharge is crowbarred near the current peak. Four parallel rail-gap switches are used on the FRCHX for this application to ensure a low-inductance crowbar discharge path and to accommodate the large magnitude of the discharge current (often greater than 1 MA). Historically, parallel operation of spark gap switches in a crowbarring arrangement has often proved to be difficult due to the very low voltage present on the bank and across the switches at the time of peak current. In a low-inductance design, triggering can be further complicated by the rapid collapse of what little voltage there is across the switches as soon as the first spark gap begins conduction. This paper reports on the efforts that were made to develop a low-inductance crowbar switch for the FRCHX and to ultimately enable successful triggering and operation of the four parallel rail-gap switches used in the crowbar. The design of the low-inductance parallel switch assembly is presented first, followed by a description of the triggering scheme employed to ensure conduction of all four switches. [ABSTRACT FROM AUTHOR]

This paper details the experimental evaluation and simulation of a 4-kV n-type gate turn-OFF thyristor (GTO) designed for pulsed power applications. The primary criteria of evaluation are rate of current rise ( dI/dt ), turn-ON delay time ( T_{D}) , and resistance of the device during turn-ON transients [ R_{\mathrm{\scriptscriptstyle ON}}(t)$ ]. The device under test (DuT) is an n-type asymmetric-blocking GTO manufactured by Silicon Power (Part No. 14N40A10) with a rated dc blocking voltage of 4 kV. A test circuit was specifically designed to minimize stray inductance in order to capitalize on the dI/dt$ capabilities of the DuT. Experimental data collected from resistance measurements are used to develop a single-switch approximate model for use in simulation. The results of dI/dt$ experiments provide a profile of DuT dI/dt$ operation beyond rated values; specifically dI/dt were readily achieved. The turn-ON delay time of the DuT is also characterized and determined to be $\sim 225$ ns on average. [ABSTRACT FROM AUTHOR]

A bipolar pulse has been proved to be more advanced in the treatment of tumor because of the elimination of muscle contractions and the effect for ablating nonuniform tissue. In this paper, a new type of modular bipolar pulsed-power generator based on Marx generator with double power charging is proposed. The concept of this generator is charging the two series of capacitors in parallel by two power sources, respectively, and then connecting the capacitors in series through solid-state switches with different control strategies. Utilizing a number of fast solid-state switches, the capacitors can be connected in series with different polarities, so that a positive or negative polarity pulse will be delivered to the load. The simulated models of this generator have been investigated in a PSPICE platform, and a laboratory prototype has been implemented in a laboratory. The simulation and test results verify the operation of the proposed topology in different switching modes. The development of this pulse generator can provide the hardware foundation for the research on biological effect without muscle contraction when the tumors are applied with bipolar pulse electric field. [ABSTRACT FROM AUTHOR]

During a disruption, plasma electromagnetic energy usually damages tokamak devices severely. Thus, this paper presents a five-part energy processing system (EPS) to dispose this energy. The five parts of the EPS are as follows: the metal oxide varistors employed to limit overvoltage and to absorb energy, the resistor module applied to consume energy, the pulse capacitor module used to store energy, the inverter module used for energy feedback, and the controller. These parts are described, and their key design features are introduced. The influence of different capacitances and resistances on the amount of energy transferred is investigated. The simulation results obtained by the Power Simulation program are given. The experimental and simulation results show that about 20%–30% of the total plasma electromagnetic energy can be transferred out of the tokamak device and effectively disposed by the EPS during the disruptions in the Joint Texas Experimental Tokamak (J-TEXT) tokamak. Moreover, the loop voltage during a disruption can be inhibited and decreases about 40%. [ABSTRACT FROM AUTHOR]

The superconducting inductive pulsed-power supply (SPPS) circuit consists of a high-temperature superconducting pulsed-power transformer (HTSPPT) and an auxiliary capacitor. The electrical losses and the power of the primary source can be cut down with the superconducting inductive energy storage. Although its energy density is slightly less than a purely superconducting inductive system, it can reduce the maximum voltage of the opening switch by the capacitor and achieve a high degree of current amplification factor. However, during the discharge process, the magnetic leakage flux energy stored in the primary of the HTSPPT requires the capacitor to have a certain capacity. The higher the ratio of the capacitive stored energy over the total inductive stored energy, the more the dominant position of inductive energy storage reduces. The current amplification factor ( \gamma ), the maximum voltage of the opening switch ( V_{S\max } ), and the ratio of capacitive stored energy ( \eta ) are the three main properties of the SPPS circuit, which depends on several intertwined critical parameters, such as the inductance ratio n = L2 /( L2+LL ) and the capacitance ( $C_{{\mathbf {1}}}$ ). This paper studies the influence of the critical parameters on the main circuit performance with a 1-kJ SPPS system. The detailed selection method of the critical parameters for the specific system is also discussed with a coupling coefficient of 0.95. Such a system is easy to be utilized for the basic experimental study of a small railgun. [ABSTRACT FROM PUBLISHER]

Low-temperature plasma treatment is a promising technology for particulate matter (PM). In this paper, the arrayed dielectric barrier discharge (DBD) plasma reactor for PM2.5 removal is investigated at atmospheric pressure. In order to reveal the interaction between experimental findings and simulation results, the equivalent electrical circuit is used. The electrical model is implemented on the PSIM software. To calculate the capacitance of the arrayed DBD reactor, the capacitor expressions are developed. Considering the experimental elements, such as plasma-generated configuration and the power source, a topological equivalent circuit is given. Finally, the simulation results are compared with the experimental ones, and they agree well. In addition, the designed DBD reactor was used to investigate PM2.5 removal. PM2.5 removal after 4 min of plasma treatment found to be about 53.8%. [ABSTRACT FROM PUBLISHER]

In this paper, a new multiple-needle-cylinder reactor is designed to study the Escherichia coli inactivation with an unstable pulsed arc discharge in water and investigate the influence of several parameters for promoting its industrial application. The results show that the inactivation rate is mainly determined by energy density. About three orders reduction can be obtained with an initial cell count of 3\times 10^5 CFU/mL and energy density around 2 J/mL. The inactivation rate can almost reach 100% when the energy density is around 8 J/mL. For reaching the maximum inactivation rate of this system, the parameters including initial water conductivity below 50~\mu \textS /cm, initial cell count over 10^4 CFU/mL, and bubbling flow rate around 3.5 L/min are recommended. The water conductivity, pH value, and concentrations of hydrogen peroxide and ozone are also measured during the treatment to evaluate their influence. The transmission electron microscopy images of E. coli indicate that the intracellular morphology changes after plasma treatment. [ABSTRACT FROM AUTHOR]

Compact, portable pulsed power technology is rapidly developed. Solid-state storage medium attracts strong interest, since it has been characterized a high power storage density and good environmental adaptability. In this paper, we use a glass-ceramic substrate, with the dimension of 250~\textrm mm\times 95~\textrm mm\times 4 mm, to deliver a high-voltage pulse with a pulse duration longer than 120 ns. In tests, both the pulse duration and the impedance are varying when we are changing the environmental dielectric from the transformer oil or air to the propylene carbonate. A theoretical model is used to analyze the phenomena and verified by the CST simulation. The dispersion analysis shows that a good dispersion characteristic is obtained in the work band of the forming pulse, although the environmental dielectric will influence the pulse duration and characteristic impedance. [ABSTRACT FROM PUBLISHER]

Miniaturized high-voltage power converter techniques might offer an improved outlook for the development of compact accelerator technologies. We view the identification of materials and circuits that provide both high-voltage isolation and efficient power coupling characteristics to be the primary engineering challenge. A lithium niobate resonant piezoelectric transformer was mated to a voltage multiplier circuit, and the input–output terminal characteristics were investigated. This paper considers the piezoelectric transformer-coupled voltage multiplier circuit as a black box and reports on the input impedance, output voltage, power conversion efficiency, and transient charging capacity. We found that the circuit was well suited to the charging capacitors of arbitrary size to voltages well over ten kilovolts at power-conversion efficiencies approaching 20%. The circuit was also quite capable of driving a vacuum diode to high voltage. The piezoresonant transformers coupled to output power conditioning circuits appear to be good candidates for producing high voltage in a small footprint. [ABSTRACT FROM PUBLISHER]

The objective of this paper is to investigate an influence of high-frequency high-voltage impulse conditioning on the back-to-back capacitor bank switching performance of vacuum interrupters (VIs). Nine identical 7.2-kV VIs were tested by 80 CO operations after the proposed conditioning. Test inrush currents were set to 0-, 2-, and 5-kA peak. The experimental results showed that this conditioning technology could make an impact on both prestrike and restrike characteristics of VIs. The complementary cumulative distribution function (CCDF) of the prestrike gap d\textrm {pre} followed complementary Weibull distribution. In contrast to VIs without conditioning, three typical prestrike gaps, i.e., CCDF 10% prestrike gap d\overline {10} , CCDF 50% prestrike gap d\overline {50} , and CCDF 90% prestrike gap d\overline {90}\vphantom {\sum RRR} , decreased by 39%, 19%, and 4% at most, respectively. Besides, the scattering of d\textrm {pre} decreased by 52% at most. Furthermore, the conditioning technology had an influence on the feature of restrike waveform through variation of field emission current. It could also reduce the restrike probability by 22.5% at most and made the entire restrikes occur between $0.5T$ and $5T$ during recovery voltage period ( $T=20$ ms). [ABSTRACT FROM AUTHOR]

The spark gap switch is the key element in any pulsed power system, which directly determines the pulse repetitive frequency of the system. The dielectric recovery data of the spark gap play a basic role, but they have not yet been adequately studied for repetitive pulse charge conditions. This paper describes some of the factors that affect the recovery of spark gap switch for pulse-charged operation. A two-pulse technique has been used, in which the first pulse is applied to the spark gap to overvolt the gap and initiate the breakdown and the second pulse is used to determine the recovery voltage of the gap. The effects of electrode size, pulse rise time, and conduction current on the spark gap recovery performance are presented. Experiments were performed by using a double-pulse generator capable of generating 40-kV pulses with a delay of 1 ms–1 s. Spark gap electrodes of 34-, 40-, and 68-mm diameters and a point type were used in the study. The effect of voltage rise rate was studied by changing the charging capacitor to 100, 500, and 1000 nF in the circuit. An intermediate plateau was observed in the spark gap recovery curves. In addition, an increase in the output impedance resulted in a decrease in the time taken for the recovery of the spark gap. Also, the switch recovery appears to be largely dependent on the electrode shape and size compared with the pulse rise time. [ABSTRACT FROM AUTHOR]

In this paper, the mathematical lifetime models of capacitors and spark switches are investigated and a linear transformer driver circuit model consisting of five 100 kV/MA cavities is built. The effect of random failures, switch jitter and prefire probability, on the module lifetime is investigated, respectively, by observing the influence on the capacitor lifetime and module output. Sensitivity analysis of time delay jitter of switches and prefire probability of switches on the module lifetime is carried out. The module lifetime prediction model is built by the combination of the lifetime model of key components, random failure model, and the module circuit model. Examples are taken to illustrate the process of module lifetime prediction and maintenance cycle determination. [ABSTRACT FROM PUBLISHER]

A 4.8-MJ capacitive pulsed-power system (PPS) was designed and fabricated for electromagnetic launcher (EML) experiment. The PPS consists of eight 600-kJ segments, which can be operated independently. In each segment, six 100-kJ capacitor bank modules, a charging power supply, a dump and charge panel, and control circuit were integrated. The capacitor bank modules in the segment are charged at the same voltage up to 10 kV, but the trigger time of each module can be set up differently. The overall PPS system is controlled by a control program, which sets charging voltage and trigger time of each module and monitors the states of system component. All the control signals are transmitted through fiber optic communication. The 48 unit modules are connected in parallel to EML with high-voltage coaxial cables. A current amplitude of more than 1 MA and a pulsewidth of several milliseconds were achieved by the PPS. The PPS has been applied to several tens of firing experiments of EML successfully. The design, fabrication, and the test results of the 4.8-MJ PPS were described in this paper. [ABSTRACT FROM PUBLISHER]