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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]

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]

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

High-power current sources with high dynamic performance, ultralow current ripple, and absolute reference tracking accuracy are the key elements for magnets (bumper and septum) that are used in accelerators. Similar requirements are also encountered in plasma research applications in fusion reactors, as well as plasma research for the future high voltage direct current circuit breakers. Therefore, the current source must be able to drive resistive/inductive and highly fluctuating loads without any compromise in its performance. In this paper, such a flexible, dynamic, and accurate current source is introduced, which able to provide amplitudes up to 30 kA and bipolar voltages up to 10 kV. The system’s operating concept is presented and its design procedure in order to fulfill a list of demanding specifications is demonstrated. In addition, a detailed description of its near-optimal, advanced control system is presented. Finally, the theoretical considerations are verified by extensive simulation results for various operating scenarios, including driving chaotic arc loads. [ABSTRACT FROM AUTHOR]

This paper proposes the equivalent circuit of postarc dynamic voltage distribution (PDVD) in multibreak vacuum circuit breakers (VCBs). The equivalent circuit is composed of controlled postarc sources, postarc resistors, and equivalent capacitors. The sheath growth and the postarc process of double-break VCBs are analyzed. The PDVD is divided into four processes: the initial transient recovery voltage (TRV) process, the oscillating TRV process, the stable TRV process, and the power-frequency voltage process, which can be analyzed by the equivalent circuit. The novel equivalent circuit of the PDVD in multibreak VCBs is gained by introducing the controlled postarc current source. The test platform is set up in the synthetic circuit. The postarc current, grading capacitor current, and the TRV are measured to analyze the PDVD in the above four processes. The test results verify the theoretical analysis. Therefore, the mechanism of the PDVD in multibreak VCBs is obtained and described by the equivalent circuit, which is useful to gain even voltage distribution and improve the breaking capacity of multibreak VCBs. [ABSTRACT FROM AUTHOR]

Power supplies have played crucial role to improve and extend plasma applications. Several dc, pulsed, and radio frequency (RF) stabilized power supplies have been developed over a wide range of frequencies and voltage waveforms. However, the influence of voltage waveform on the plasma densification, mainly due to the secondary electrons emission from the electrodes, has not been quite explored. This paper proposes an asymmetric pulsed bipolar power supply, adjustable in frequency, amplitude, pulsewidth, and number of pulses for generation of cold plasmas. Short period positive pulses, between longer negative pulses, increase greatly the secondary electron emission from the electrodes and, consequently, the plasma ionization rate. Short pulses (ns) are obtained by the phase shift between each carrier, and the high-intensity pulses are obtained by cascading the cell submodules in a half-bridge cascade topology, using a modular half-bridge converter configuration. The intensity of the positive and negative pulses can be varied independently. There is no unintended dc voltage level between the electrodes, which appear in RF plasmas. The plasma generated in this way is free of electric arc and can be kept stable within a broader range of operating parameters, mainly the voltage and the working gas pressure. [ABSTRACT FROM AUTHOR]

Risk of arcing in space plasma environment on satellite solar panel has always been an issue of major concern in the aerospace community. The outcome of round robin tests performed in various laboratories has resulted in finalization of the guidelines for the ground test of satellite solar panel coupons (SSPCs). This is documented as ISO-11221 standards. Authenticity of arc plasma flashover (FO) parameters are still under debate. Some experimental findings that support the perimeter theory of arc FO on geostationary (GEO) satellites are discussed in this paper. It has been observed that characteristics of an the arc are dependent on its location on the solar coupon, bias charge (charge due to bias voltage and external capacitance), and the total charge dissipated during the arc discharge. It is also observed that the duration between the two consecutive arcs is directly proportional to the dissipated charge or energy of the latter arc. A combined dielectric consisting of solar cell, adhesive, Kapton, and Carbon Fiber Reinforced Polymer sheet holds charge during irradiation by the electron gun. This resembles surface FO capacitance. Arc energy is governed by the combined effects of a surface flashover capacitor (C-sf) and an external capacitor. It is observed that if intermittent arc duration is sufficiently longer than the gradual accumulation of charge on the SSPC, body may lead to a major arc. This would increase the probability of secondary arcs when the sustained arc environment is experienced by the satellite. To understand primary arcs on dielectrics, an artificial triple junction is prepared and exposed under adverse GEO-like space conditions. Various signatures identified from the arc current and arc neutralization current waveforms specify the behavior of these arcs at different locations on the coupon surface. In this paper, current waveforms of arcs captured on different types of solar panel coupons and their significance are studied. Information about arc energy, arc velocity, and neutralization velocity are extracted from the measured waveforms. [ABSTRACT FROM PUBLISHER]

In JT-60SA, the control of resistive-wall-mode (RWM) instabilities will also be realized with a dedicated active control system based on 18 in-vessel sector coils. Each coil will be fed independently by a dedicated fast inverter. Due to the outstanding dynamic performance required, new insulated-gate bipolar transistor modules based on silicon carbide (SiC) have been adopted. Being capable to switch at 30 kHz, these components, together with a very fast control system, allow reaching the required high dynamic performance with the simple and compact H-bridge topology. The RWM-PS will be the first power supply system for fast control of plasma instabilities in fusion experiments adopting SiC semiconductors. This paper gives an overview of the final design of the RWM-PS, with particular emphasis on its special features and the solutions implemented to satisfy the critical requirements. The issues related with the high switching frequency and the peculiar nature of the load will be treated in detail. [ABSTRACT FROM AUTHOR]

Water can be activated by applying plasma to water, for instance, by creating plasma inside (bubbles in) the water, or along a water surface. Plasma-activated water (PAW) typically contains hydrogen peroxide, nitrates, nitrites, and peroxynitrite, and typically has a pH ranging from 2 to 4. The components of PAW and the low pH have proven synergistic antimicrobial effects against bacteria, biofilms, yeasts, and other microorganisms. This paper describes a power modulator and a plasma reactor system for high-yield production of PAW at high production rate. A compact and solid-state dual resonant system has been realized and successfully demonstrated for industrial PAW production. The system generates up to 80-kV (theoretical 120 kV is possible) dual-resonant high-voltage pulses with an oscillation frequency up to 2 MHz, pulse repetition rate > 20 kHz, and an average power of 800-W continuous. In addition to the power modulator, the PAW production system consists of a transient arc plasma reactor and a loop system. Depending on the application, the system is able to activate 10–100 L/h. The disinfecting properties of the PAW production system have been verified by experiments on the reduction of Staphylococcus Epidermidis. Directly after its production, the log reduction of S. Epidermidis can be as high as >8 log. During a period of at least 40 min after its production, the PAW has “mild” disinfecting properties, being able to deactivate S. Epidermidis by 3–4.1 log. [ABSTRACT FROM PUBLISHER]

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]

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]

This paper covers ongoing research on pulsed-power-produced plasmas using wire arrays and foil loads at four universities in the U.S. It is directed toward prospective and current students, as well as program managers at government agencies, and others who have a general interest in applications of pulsed power. This paper presents several pinch configurations (Z-pinches, X-pinches, planar wire arrays, radial, and suspended foils), specific physics issues (e.g., wire ablation), applications (plasma jets, X-ray hohlraums), diagnostics (e.g., ultraviolet laser probing), and modeling. The areas covered are not meant to be comprehensive, but rather, the discussion demonstrates the breadth and vibrancy of the activities at these institutions and collates extensive references on this work over primarily the past six years. [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 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]

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]

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]

The results of a miniature plasma focus are presented in this paper which is operated with energy less than or equal to 150 J. The miniature plasma focus is driven by a small capacitor bank and the peak current delivered in the focus is 75–80 kA. The deuterium gas is filled with a pressure range of 5–7 mbar inside the plasma focus chamber. The quartz glass is used for generating initial surface breakdown at a 4–5-kV discharge, which is a typical value for low-voltage plasma focus discharges. The repetitive operation (record 50 Hz) of the device is achieved by a combination of a simple and high power (5 kW) supply with the synchronized triggering of the capacitor bank at the time of isolation between supply and the capacitor bank. The diameter of cathode is 25 mm and anode diameter is 8–12 mm and both of them are made of stainless steel. The length of anode and gas pressure is adjusted in such a way that the pinching occurs at the time of occurrence of the peak of current. It enhances the neutron emission from the device. The time-of-flight diagnostic is used to distinguish neutron and X-ray emission from the plasma focus. The neutron measurement using a helium-3 detector and also a fast-scintillator-backed photomultiplier tube demonstrates production of neutron pulses in the time separated by nearly 20 ms, which corresponds to 50 Hz in the burst mode. The device can serve the purpose of being a portable and compact repetitive neutron source for various applications as the flux of the radiation is comparable with that of bigger plasma focus operating at the similar current. [ABSTRACT FROM PUBLISHER]

The impedance matching circuit is the important unit for the RF ion source, which is used to match the electric parameters of the RF generator and ion source antenna in order to transfer the RF power to the RF antenna of ion source and to get stable plasma. The plasma impedance will be changed during the plasma generation, since the impedance characteristic is not easy to be calculated and measured; it also necessary to do more experimental study. In this paper, the impedance matching unit was analyzed and designed according to the principle of RF ion source. The matching characteristic was studied during the experiment, and we achieved the best impedance matching characteristic. It also verified the good design of impedance matching unit. Based on the results of impedance matching studies, high-RF stable plasma discharge was achieved. [ABSTRACT FROM AUTHOR]

The electrical characteristics of pulsed-discharge plasma for decoloration of dyes in water were systematically investigated with a view toward getting insight into discharge process. Methylene blue (MB) dye water was selected as the target object. The discharge behavior was found to depend on the power supply voltage, conductivity of MB solution, and pulse-forming capacity. A strong positive linear relationship existed between power supply voltage and initial capacitor voltage. The injection energy per pulse increased when increasing the power supply voltage and a maximal energy efficiency of injection of approximately 85% was obtained at power supply voltage of 50 V. The conductivity of MB solution had appreciable impact on the voltage-current characteristics and discharge time of pulse-forming capacitor. Remarkable increase of pulse current was observed as the pulse-forming capacity increasing, while it had slight effect on the pulse voltage. The pulsed corona discharge in MB solution could change into spark discharge by way of increasing the air flow rate and reducing the electrode distance. Increasing pulse-forming capacity and pulse frequency significantly accelerated the decoloration rate of MB in solution. This paper is expected to provide reference for improving the application of pulsed-discharge plasma in treating dye solution. [ABSTRACT FROM PUBLISHER]

Silicon-avalanche-shaper (SAS) diodes are fast-closing switches capable of producing high-voltage pulses with a rise time of $\sim 100$ ps. The SAS can be driven by a positive, nanosecond scale, high-voltage pulse applied to its cathode where the magnitude of the driving pulse is correlated to the magnitude of the pulse at the SAS anode (output). Drift-step-recovery diodes (DSRDs) are fast-opening switches capable of producing high-voltage pulses with a rise time of the order of 1 ns. Thus, DSRDs are good candidates for driving SAS diodes. In this paper, the SAS output is studied with respect to its driving conditions. First, the SAS output is examined with respect to the magnitude and rise time of the driving pulse, utilizing three DSRDs to produce pulses with various rise times from 0.5 to 5 ns. In addition, the effect of the driving pulse repetition frequency (PRF) on the SAS output is studied. An experimental demonstration using a 1.5-kV SAS fabricated at the Ioffe Physical Technical Institute shows the advantage of driving the SAS with the short, 0.5 ns, pulses, and the degradation of performance due to high PRF, up to 10 MHz. [ABSTRACT FROM PUBLISHER]

Experimental results on atmospheric-pressure arc plasma convolutes in air around a polytetrafluoroethylene cylindrical shroud containing a magnetic field (B-field) producing coil are presented. In this paper, the B-field coil is energized by a current separate from that flowing through the arc, and a separate RLC circuit was connected across the arc gap. Thus the magnitude and time duration of the B-field are independent of the arc current and the high-frequency current oscillations produced by the parallel RLC circuit. Experimental results for the time variation of the current through and voltage across the arc plasma for these different conditions are presented, along with high-speed photographs of the oscillating current arc. The effects of varying the B-field upon plasma pulsations formed by the independent B-field and RLC current oscillations are discussed. [ABSTRACT FROM AUTHOR]

Railguns have the experimentally proven capability to accelerate masses of several kilograms to velocities in excess of 2 km/s. The U.S. ONR railgun project demonstrates that the military application of such high-performance railguns is becoming a realistic possibility in the nearer future. Up to now, the research at the French–German Research Institute of Saint-Louis (ISL) concentrates on reaching velocities of about 2.5 km/s with 300-g projectiles. The current research project is aimed at developing a realistic payload for the railgun projectile. At the same time, it is attempted to increase the used primary energy. Within this new multiyear research program, sponsored by the French and German defense agencies, the first step is to develop 600-g projectiles (with approximately 50% payload) and accelerate these to at least 2000 m/s. This paper reports on the results of experiments with two different types of projectiles at energy levels of up to 4.3 MJ. [ABSTRACT FROM PUBLISHER]

This paper describes a low cost, easy-to-implement circuit for triggering ignitrons in plasma physics experiments and other pulsed power applications. Using insulated gate bipolar transistors (IGBTs) for rapid switching, the circuit delivers >200~A peak current from a 0.1-\muF capacitor to the ignitron trigger pin with a rise time of \sim0.6~\mus. The trigger circuit is isolated from the ignitron by a pulse transformer. Details of the circuit design and practical considerations for working with IGBTs are discussed. Sources of inductance in the system are identified, and leakage inductance associated with the pulse transformer is shown to be the primary factor limiting the pulse rise time. [ABSTRACT FROM PUBLISHER]

This paper reports the results of characterization and optimization experiments carried out on a newly developed NX-3 dense plasma focus device (20 kJ at 20 kV, a quarter time period of \sim\!\!3\ \mu\s, and 10 kJ/600 kA at 14 kV) at the Plasma Radiation Source Laboratory, NIE, Nanyang Technological University, Singapore. Initial experiments were conducted with an electrode assembly configuration having anode radius and length of 20 and 160 mm, respectively, for detailed neutron emission characterization of NX-3 device followed by further optimization of neutron yield using various other electrode configurations designed using the Lee Code. At \geq10-kJ operation, the average neutron yield on the order of 10^9 neutrons/pulse in 4\pi\sr was obtained for the deuterium filling gas pressure range of 6–8 mbar. The neutron yield of \sim\!\!4.6 \times 10^9 neutrons/pulse at 10 kJ/6 mbar is the highest ever reported for a device with the same stored energy. The neutron anisotropy measurements point to the beam–target mechanism as the dominant neutron production mechanism for NX-3 plasma focus device. Further optimization of neutron yield in NX-3 was achieved with the peak average neutron yield being enhanced from \sim\!\!(2.38 \pm 0.31) \times 10^9 neutrons/shot for the initial electrode configuration to about \sim\!\!(3.40 \pm 0.43) \times 10^9 neutrons/shot for the electrode configuration with anode radius and length of 26 and 140 mm, respectively. The analysis of neutron yield results for various electrode assembly configurations demonstrates the speed factor as a key optimization tool for maximization of neutron yield. [ABSTRACT FROM PUBLISHER]

A conductive plasma channel in the shape of a 360◦ helical arc has been realized via the mechanisms of electromagnetic induction and exploding wire (EW). This paper is focused on documenting the restrike (RS) mechanism for a wire exploded via electromagnetic induction. The apparatus is a pair of mutually coupled helical coils, which are arranged on cylindrical polyvinylchloride formers, with a capacitor bank as the energy source. Voltage and current waveforms are presented. The wire explosion by induction exhibits key features that exist in conventional wire explosion by conduction, namely, wire fragmentation, a dwell period, and RS phenomena. Exponential damping envelopes were graphically applied to distinguish between RS and non-RS outcomes of the wire explosions. Photography, visual observation, and copper oxide residue patterns also helped to determine whether an RS took place. Lichtenburg figures in the form of dust trees were found to have formed at some time during the induced EW discharge. [ABSTRACT FROM PUBLISHER]

Shunting discharge plasmas are metal plasmas that can be generated around a conductive rod at a reduced pressure on the order of 0.1–100 Pa. Even at atmospheric pressure, a plasma can be generated because the rod is heated to emit metal vapor so as to generate gas breakdown around the rod. When the temporally increasing voltage across the rod matches the plasma ignition voltage, a shunting plasma is ignited. The plasma ignition is triggerless and, thus, does not require an external signal. There are two types of shunting plasmas: glow and arc discharges, with sustenance voltages of approximately 100 and 60 V, respectively. The plasma results in an arc discharge via a glow state. When a pulsed-power source with a controlled pulse duration is used to obtain a glow plasma only, a stable steady-state glow can be obtained under a suppressed current with a duration of over 10 \mu\s and a consumed power of several tens of kilowatts. A shunting glow plasma can be realized by controlling the pulse duration. In this paper, optical emission spectra from the shunting glow and shunting arc are observed. Singly charged carbon ions were found to be produced by the glow plasma. Carbon emission was significant in a nitrogen gas environment, as compared with an argon environment. In the case of a shunting arc, the optical emission is broad in wavelength, and doubly ionized carbon species also arise. A preliminary test of diamond-like carbon (DLC) film deposition was carried out, where the DLC was deposited on a substrate set near a plasma source. The DLC state was determined using Raman spectroscopy, and no macroparticles were found on the deposited film, which had a clean surface. The rod holder used as an electrode showed no damage. In contrast, in the case of a shunting arc, many macroparticles were found on the deposited films, and serious damage to the electrode also occurred. [ABSTRACT FROM PUBLISHER]

Thin film produced by exploding wires is affected by many factors; one of such factors is the energy depositing rate. The research in this paper focused on measuring the voltage and current of an exploding copper wire that was 15 cm long and 0.3 mm in diameter. The time-dependent wire resistance and the energy deposited into the wire were deduced from the measured voltage and current, and the maximum wire resistance was observed at the time when part of the wire mass was heated up to the boiling point, which was called critical time and critical point, respectively. From the experiment, the following statements could be surmised: The maximum wire resistance increases from about 224.4 to 266.1 \m\Omega, and the critical time reduces from about 8.8 to 7.2 \mu\s when the initial capacitor voltage changes from 10 to 20 kV, as well as the fact that the mean energy depositing rate varies from about 13.3 to 27.6 \J/\mu\s before the critical point. Also, thin copper film is prepared by this method under initial capacitor voltages of 10, 15, and 20 kV, respectively. The SEM micrographs of the film samples are also presented and analyzed. This result demonstrates that a faster energy depositing rate can help to heat up the wire mass more uniformly and more wire mass would evaporate before the critical time to create a greater wire resistance at the critical point, and the film surface is more uniform and has less void fraction. [ABSTRACT FROM AUTHOR]

This paper presents a high-voltage pulsed-power system based on low-voltage switch–capacitor units that are connected to a current source for several applications such as plasma systems. A modified positive buck–boost converter topology is used to utilize the current source concept, and a series of low-voltage switch–capacitor units is connected to the current source in order to provide a high voltage with a high voltage stress (dv/dt) as demanded by the loads. This pulsed-power converter is flexible in terms of energy control because the stored energy in the current source can be adjusted by changing the current magnitude to significantly improve the efficiency of various systems with different requirements. The output-voltage magnitude and stress (dv/dt) can be controlled by a proper selection of components and control algorithm to turn on and off the switching devices. [ABSTRACT FROM PUBLISHER]

In this paper, the effect of the capacitance of a variable capacitor connected on the ground side of a ferrite-enhanced internal U-type inductively coupled plasma (ICP) source on the electrical characteristics of an ICP antenna and the plasma characteristics is investigated. When the capacitance of the variable capacitor satisfies C = 2/\omega^2L (where \omega is the angular power RF frequency and L is the antenna inductance), the highest plasma density of 2.74 \times 10^11/ \cm^3 and the lowest plasma potential of about 19.5 eV are obtained at a 13.56-MHz RF power of 400 W and 10-mtorr Ar. In addition, under these conditions, the best plasma uniformity of about 6% over a substrate area of 300 mm and the most stable operating conditions, due to the lowest heating of the ferrite installed on the ICP antenna, are obtained. The capacitance condition of C = 2/ \omega^2L is related to the minimization of the capacitive coupling to the plasma due to the lowest peak RF voltage being obtained along the antenna line. It is also related to the maximization of the power-transfer efficiency to the plasma by minimizing the power loss to the ferrite installed on the ICP antenna, due to the lowest peak RF current being obtained along the antenna line. [ABSTRACT FROM PUBLISHER]

This paper describes the construction and experimental tests of a 12-kV high-voltage high-action generator based on reverse-switching dynistor (RSD) assembly. The main RSD unit consists of seven 76-mm-diameter dynistor pieces connected in series with a blocking voltage of about 2.4 kV, a magnetic switch based on a 1K101 amorphous alloy core, the trigger system based on a saturable transformer, and a 16-mm RSD assembly; the trigger current could reach 2 kA in amplitude with 1-\mu\s duration under 10 kV. The working voltage rate of this RSD unit is about 8–12 kV. Experiment on a 2.2-mF capacitor test bed under 12 kV working voltage, the switch current amplitude reached 150 kA with 300-\mu\s duration; the transferred charge is about 26.5 C and the action is 2.94 \MA^2\s, respectively. [ABSTRACT FROM AUTHOR]

Nonequilibrium atmospheric plasma jets are associated with sequence of streamer breakdowns developing in helium-air mixture. In this paper, propagation of the streamer in plane capacitor is photographed, and deflection toward the positive capacitor plate is analyzed. [ABSTRACT FROM PUBLISHER]