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In this paper, two designs of the rectangle-pulse Marx generator based on pulse-forming network (PFN) for pulse-power application are reported. The PFN is composed of inductors and capacitors. Proposed schemes consist of several identical PFNs that are connected according to Marx generator scheme. PFN Marx generators can output rectangle pulse several hundreds of nanoseconds in duration and several tens of nanoseconds in rising time. The effect of component parameter to the waveform is studied. Prototypes made of four PFNs have been tested. One of the prototypes is designed according to classical Marx mode, while another is designed as an L--C Marx generator in which only one command switch and one isolating switch is needed. In a 500-ns duration, 65-ns rising-time rectangle pulse has been achieved on the matching load. Index Terms--Classical mode, L--C mode, Marx generator, pulse-forming network (PFN), rectangle pulse.

High voltage pulsed power supply using IGBT (Insulated Gate Bipolar Transistor) stacks and pulse transformer for plasma source ion implantation is proposed. To increase voltage rating, twelve IGBTs are used in series at each IGBT stack and a step-up pulse transformer is utilized. To increase the current rating, the proposed system makes use of synchronized three pulse generator modules composed of diodes, capacitors and IGBT stacks. The proposed pulsed power supply uses semiconductor switches as main switches. Hence, the system is compact, and has semi-infinite lifetime. In addition, it has high flexibility in parameters such as voltage magnitude (10-60 kV), pulse repetition rate (PRR) (10-2000 pps), and pulse width (2-5 [micro]S). Index Terms--Pulsed power supply, IGBT stack, semiconductor switch.

High voltage Marx generator implementation using IGBT (Insulated Gate Bipolar Transistor) stacks is proposed in this paper. To protect the Marx generator at the moment of breakdown, AOCP (Active Over-Current Protection) part is included. The Marx generator is composed of 12 stages and each stage is made of IGBT stacks, two diode stacks, and capacitors. IGBT stack is used as a single switch. Diode stacks and inductors are used to charge the high voltage capacitor at each stage without power loss. These are also used to isolate input and high voltage negative output in high voltage generation mode. The proposed Marx generator implementation uses IGBT stack with a simple driver and has modular design. This system structure gives compactness and easiness to implement the total system. Some experimental and simulated results are included to verify the system performances in this paper. Index Terms--Pulsed power supply, IGBT stack, AOCP, Marx generator.

This paper describes a newly developed novel repetitive impulse voltage generator using a boost converter array. To solve problems such as short life time, low operating frequency, and the fixed pulse width of conventional generators, the proposed generator is designed with a boost converter array that employs series-connected capacitors and insulated gate bipolar transistors. The circuit can easily obtain a high-voltage pulse without any high-voltage direct current source and pulse transformer. Thus, the proposed circuit not only allows elimination of the expensive high-frequency transformer but also allows operation at a frequency up to several kilohertz with high reliability and longer life span. To validate the proposed circuit, two pulse generators rated at 1.8 kV, 40 A and 20 kV, 300 A are implemented and tested. Index Terms--Boost converter, pulse generator, pulsed power, series-connection.

This paper presents a novel crowbar circuit for a 50-kJ capacitor hank. The crowbar circuit consists of a Rogowski coil, a trigger signal generator, and a triggered vacuum switch (crowbar switch). In our crowbar circuit, the Rogowski coil senses the load current and generates trigger signals at the correct time for the crowbar switch operation. At full capacitor charge voltage of 22 kV, it was possible to keep the reverse voltage of the capacitor below 15% of charging voltage. In this paper, we report the features of our crowbar switch system and the electrical performance of the crowbar system Index Terms--Capacitor bank, crowbar circuit, crowbar switch, pulsed power, Rogowski coil.

In this paper, the C[F.sub.4] decomposition efficiency is investigated for three simulated plasma reactors: needle-plate reactor (NPR); metal-particle reactor (MPR); and dielectric-barrier reactor with hole (DBH). The C[F.sub.4] decomposition efficiency by DBH is much better than that by NPR or MPR. When applied voltage is increased up to the critical voltage for spark formation in the all reactors, the C[F.sub.4] decomposition efficiency is increased. The C[F.sub.4] decomposition efficiency in NPR and MPR is about 12% and 22%, respectively, at an applied voltage of 23 kV (consumption power: 110 W) and C[F.sub.4] concentration of 500 p/min, however, the C[F.sub.4] decomposition efficiency is higher than 95% in the case of DBH. The DBH should be much better than two reactors investigated for C[F.sub.4] decomposition. Index Terms--C[F.sub.4], decomposition, dielectric-barrier reactor with hole (DBH), metal-particle reactor (MPR), needle-plate reactor (NPR).

The designing of square pulse generators using pulse-forming lines (PFLs) made up of identical L and C, was reviewed in this study. Fourteen different types of PFLs were analyzed utilizing PSpice simulation results. These PFLs are described with respect to their distinct features--the number of forming lines (single or double), the circuit relationship of the PFL and load (parallel or series), and the types of energy storage (current source, voltage source or a combination of both). The characteristic impedance, output parameters such as pulsewidth, voltage and current magnitudes, and pulse power were derived for each scheme. The merits and demerits of the output parameters are also included. Index Terms--Generators, pulse forming lines (PFLs).

A semi-analytic model of collisionless sheath in plasma immersion ion implantation (P[I.sup.3]) for a step bias with finite rise time in cylindrical geometry has been developed. The model takes into account the formation of the presheath, predicts the sheath overshooting and its further recovery to the steady-state Child value. To verify the model, a sheath dynamics has been investigated experimentally on a 30-kV P[I.sup.3] setup using the positively biased Langmuir probe technique. The measurements have been carried out in argon and helium plasmas of inductively coupled and hot cathode plasma sources. The model predictions agreed well with the experimental results. Index Terms--Modeling, plasma and sheath measurements, plasma immersion ion implantation, sheath.

The design technology of a closing switch, especially inverse pinch switch (IPS) triggered by [N.sub.2] gas for a high voltage and current is described in this paper. Also, the capacitor banks, control system, dc charging system, and high-current cable system, etc., are introduced. In contrast to a conventional trigatron switch in which the current is constricted by a z-pinch mechanism, the new switch operates in an inverse-pinch geometry formed by a metal chamber, greatly reducing hot-spot formations on the electrode surfaces. A prototype of the IPS with a [N.sub.2] gas-puffing trigger was fabricated for breaking a large current up to 250 kA. The geometry of the IPS not only eliminates the z-pinch effects, but utilizes J x B = F force for reducing the current density. Force acting on the plasma is directed radially outward in the IPS. The annular current path is radially dispersed, which results in a low current density, running-arc mode, and a low inductance. It was shown that in comparison with the spark gap, the switch inductance and current density of the IPS are largely reduced and the useful lifetime is significantly increased. The IPS enabled the closing of very high voltage and current. Index Terms--Capacitor bank, gas-puffing switch, inverse pinch switch, isotropic discharge, pulsed power.

A pulse generator of a one-stage magnetic pulse compression (MPC) modulator, which has an average power of 7.5 kW, was developed. The modulator consists of a constant-current capacitor charger (max. 21.7 kV, 300 Hz), an initial charge capacitor (0.2 [micro]F, 40 kV), a thyratron switch, a pulse transformer with a turn ratio of 1 to 8, ceramic capacitors (2.7 nF, 160 kV), and a magnetic switch. The output voltage, current and the pulsewidth of the modulator were measured to be 85.6 kV, 1.88 kA, and 200 ns (full width half maximum) respectively, with the initial charging voltage of 20 kV. This modulator system can be operated at the maximum repetition rate of 300 Hz and the energy delivery efficiency from the initial charge capacitor to the dummy load is estimated as 55%. The pulse generator is applied to a reactor of pin-to-hole type to investigate the impedance matching between the pulse generator and the reactor, and the experimental results are presented. Index Terms--Impedance matching, N[O.sub.x], pulse generator, reactor.

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]

Graphite rods of 2 mm in diameter and 50 mm in length have been exploded in water to produce graphite nanoparticles with electrical energy from 5.5 to 44 kJ. The products of the explosion consisted of some fragments in a few micrometer size and many nanoparticles in diameter of several tens of nanometer. It is considered that local pressure and temperature were enough to convert the graphite rod to liquid droplets, which turned to the spherical shape of graphite nanoparticles by rapid cooling. The paramagnetism of the graphite nanopowder prepared in water has been revealed by vibrating sample magnetometer results. The degree of magnetization was proportional to the discharge energy and its maximum reached up to 0.56 emu/g. [ABSTRACT FROM PUBLISHER]

This paper reviews the research and development results achieved in the Korea Electrotechnology Research Institute (KERI) in a decade. KERI develops pulsed power technology and its applications are mostly based on power electronics. KERI's research and development activity covers components, military systems, and industry applications. High-voltage switching means developed in KERI are a rotary arc gap (RAG) switch (11 kV and 400 kAp), a vacuum RAG (20 kV and 150 kAp), an inverse pinch switch (20 kV and 150 kAp), and 10-kV semiconductor switch stacks made of thyristors and Insulated Gate Bipolar Transistors (IGBTs). The IGBT and thyristor stacks consist of 10 or 12 1.2-kV discrete devices and are operated by only one active drive circuit installed in the groundside. Some ferromagnetic opening switch schemes are also researched on trial bases. Some of KERI's research and development works from devices to application systems will be described. [ABSTRACT FROM AUTHOR]

This paper describes the design and analysis of a 42-kW (14 kV, 3 A) high-voltage power supply for a 30-kW industrial magnetron drive. The design is based on a series resonant converter in discontinuous conduction mode (DCM) to take advantage of both the superior arc protection stemming from the current source characteristics and the high power density owing to the use of parasitic elements such as the leakage inductance in the high-voltage transformer. The detailed design procedure for the resonant tank and high-voltage transformer with respect to the input and output specifications is described on the basis of a simplified analysis of the DCM series resonant converter. Special considerations for designing high-power high-voltage power supplies are provided, such as series stacking of diodes for a voltage doubling rectifier and insulation between each winding of the high-voltage transformer. In addition, a comparative study using theoretical equations, simulation, and experimental results was carried out. This study yielded the output voltage and current characteristics at different switching frequencies and verified the advantages of this topology, such as arc protection without an additional protection circuit and high efficiency due to zero-current or zero-voltage switching. Moreover, the parallel operation of two converters with phase shifted gating signal is proposed to reduce the output current ripple and increase power capability for higher power magnetron drive. Additionally, the design considerations of two auxiliary power supplies (a filament power supply: 15 V, 150 A and a magnet power supply: 50 V, 5 A) are also provided and optimized for effective driving industrial magnetron. Finally, the developed power supply was tested with a 30-kW industrial magnetron, and the results prove the reliability and robustness of the proposed scheme. [ABSTRACT FROM PUBLISHER]

Presents a study which investigated a rotating arc gap switch driven by self-induced magnetic field. Construction and operation of the rag switch; Experimental setup; Results of the study; Conclusion.

Presents a study which described pulse generators that use the semiconductor switches and nonlinear capacitors. Application of pulsed power compressors; Conclusion.

Presents information on a study relating to zero-voltage-transition (ZVT) pulse-width-modulation (PWM) multiphase converters. Methodology used to conduct the study; How to achieve high-performance and high power-density converters; Results and conclusion of the study.

Silicon, a nonmetallic material that cannot be exploded by wire explosion in a gaseous atmosphere, was successfully exploded in distilled water. The explosion features of the Si rod were very similar to those of metal wires. The energies deposited in a single rod were estimated using the current drop and rise points in the discharge waveform, and they found to be in good agreement with the thermodynamic data for the vaporization and ionization energies of silicon, respectively. The particles produced by the explosion have a spherical shape with a range of 20 to 200 nm diameter for nanosized SiO2 powder. [ABSTRACT FROM AUTHOR]

An experimental study of the combustion of superfine aluminum powders (average particle diameter as ∼ 0.1 μm) in air is reported. The formation of aluminum nitride during the combustion of aluminum in air and the influence of combustion conditions on the structures and compositions of the final products are addressed. The experiments were conducted in static air at 1 atm. Superfine aluminum powders were produced by exploding an electrically heated wire. Such a superfine aluminum powder is stable in air, but once ignited can burn in a self-sustaining way due to its low bulk density (∼0.1 g/cm3) and low thermal conductivity. During combustion, the temperature and radiation were measured; also the burning was recorded by a video camera. Scanning electron microscopy, X-ray diffraction and chemical analysis were performed on both the initial powders and final products. It was found that the powders ignited by local heating and burned in a two-stage self-propagating regime. The products of the first stage consisted of unreacted aluminum (∼70 mass %) and amorphous oxides with traces of AlN. After the second stage, the AlN content exceeded 50% and the residual Al content decreased to ∼10%. A qualitative discussion is given of the kinetic limitations for the oxidation of AlN due to rapid condensation and encapsulation of gaseous AlN. [Copyright &y& Elsevier]