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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 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]

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.

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 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]

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]

The process of passivation of superfine aluminum powders (SFAPs) (as≤100 nm), obtained with the electrical explosion of wires (EEW) method, has been studied. The passivation coatings of different nature (oxides, stearic acid and aluminum diboride) were covered on the particle surface. The process of passivation and analysis of passivated powders was studied by X-ray photoelectron spectroscopy (XPS), XRD, TEM, infrared spectroscopy (IR), mass spectrometry (MS), thermocouple method and bomb calorimetry. After the comprehensive testing of coatings, a model of stabilization of the superfine aluminum particles was suggested, explaining the anomalous high content of aluminum metal in the electroexplosive powders. The main characteristic of the model is a formation of charged structures, which prevent metal oxidation. [Copyright &y& Elsevier]