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The long-term goal of the described experiments is to construct multi-gap pseudospark switches, which can handle reliably the specifications of the pulse forming network (PFN) for the injection/extraction kicker magnet system of the future heavy ion synchrotron accelerator complex SIS100/300 at the Gesellschaft fuer Schwerionenforschung (GSI). The PFN requires an high-voltage switch, that can handle an hold-off voltage up to 70 kV, peak currents up to 6 kA and pulse durations up to 7 [micro]s. In this paper most of the reported experimental data have been obtained by using a two-gap prototype pseudospark switch with total hold-off voltage up to 30 kV. There are two major problems correlated with the development of such multi-gap systems. The first one concerns efficient and reliable triggering of switch for the overall switch lifetime. Two trigger systems have been studied, the so-called high-dielectric trigger (HDT), which already has proven its long term capability, and second, a novel system, based upon the electron emission from carbon nanotubes (CNT). The CNT-trigger still suffers from an insufficient small lifetime of [10.sup.4] discharges. The second critical part concerns the instant breakdown initiation in the individual gaps, separated by a drift space. In the experiments with this prototype an active pre-ionization of the drift space was nor foreseen. For both trigger systems the measured delay and jitter in the first gap vary from 50 to 60 ns and 15 to 30 ns, respectively; corresponding the second gap has a delay and a jitter of up to 200 and 45 ns, respectively. Index Terms--Hollow cathode, pseudospark switches, pulsed-power application, trigger system.

Transmission line transformers (TLT's) as pulse transformers have received increasingly more attention due to their excellent frequency response characteristics over conventional wound transformers. This transformer basically consists of equal lengths of transmission line (normally coaxial cables are used) connected in parallel at the input side of the transformer, and in series at the output side so that the output voltage can be boosted in proportion. Because the reactance of the outer conductor increases with the rise of the frequency of the input voltage, the output voltage of each transmission line can be isolated mutually when the frequency is high enough. Then, the output voltage will be amplified through the voltage superposition. To minimize the substantial loss of voltage gain and obtain a low pulse droop rate, one stage transformer is entwined together as a unit, the number of stages of the transformer can increase easily by piling units one by one. This spiral construction makes the transmission line transformers much more compact. On the other hand, with the development of modern semiconductor technology, high voltage, fast rise time power semiconductor devices have been produced, the collector emitter breakdown voltage of one IGBT is to 1.7 kV and the rise time is 100 ns. This paper describes a kind of compact pulse power supply constructed by combining transmission line transformer and modern power semiconductor devices--IGBTs. High voltage IGBTs ([V.sub.CES]=1.7 kV) have been used as charge switches, short pulses can be obtained at the input port of the transformer, then the output pulse amplitude is 10 kV through a 10-stage transmission line transformer. Finally, the output voltage pulse waveforms are given in the paper. Index Terms--Pulse power system, power semiconductor devices, transformers.

Nanosecond and sub-nanosecond high voltage pulses can provide new applications. A cancer treatment by an ultra-short pulse high electric field is one of them. High power pulsed microwave has been proposed to apply the high electric field for that treatment. This work focuses on the design of a compact high power pulsed microwave generator using a nanosecond pulse power generator for the cancer treatment. To obtain fast rise time of voltage and current for nanosecond pulses, a switch has to have low inductance. Water gap switches have this property. Since water has a dielectric strength exceeding 1 MV/cm, gap distances for switching can be reduced to several hundreds of micrometers, and still allow switching of tens of kV. The narrow gaps allow us to reduce the switch inductance. In this study, the water gap switch was built in a Blumlein pulse forming line. The Blumlein line was designed to provide a pulse of 1 ns and to match an impedance to 16 [ohms] of an antenna. By using the water gap switch in the Blumlein line, the voltage rise time obtained approximately 750 ps at 13 kV of a peak pulse voltage. An electromagnetic wave was radiated underwater by the loop antenna. A measuring antenna at 0.15 m and 0.4 m from the radiating antenna caught electric field intensities of 116 kV/m and 32 kV/m, respectively. A frequency element of 250 MHz had higher intensity. Index Terms--Nanosecond high voltage pulse, pulsed power generator, water gap switch, electromagnetic wave, radiation in water.

A general temporal coupled-mode theory for multimode optical resonators is developed, which proves a general criterion for the existence of nonorthogonal modes in passive optical resonator systems. This theory includes a formal description of a direct transmission pathway, and is capable of describing Fano interference phenomena in multimode cavities.

A new electrostatically actuated microelectromechanical series switch for switching dc to radio frequency (RF) signals is presented. The S-shaped film actuator principle allows a high isolation and low actuation voltage even with large switching areas.

The coupling behavior during the turn-off intervals of the main switches in a three-phase boost power-factor corrector composed of three single-phase modules is analyzed in this letter. Also, the rejoining of the split inductor currents of the same phase will be proven theoretically and verified with experiments. Index Terms--Coupling behavior, split input currents, three-phase boost power-factor corrector.

A study was conducted on the use of ferroelectric materials for a variety of applications and the development of analytical models to evaluate ferroelectric charge switching behavior. The experiment presents an analytical model which combines a phenomenological equivalent circuit with physics-based operation equations. The model is programmed by means of SPICE-derived device-simulation software, is compact and requires minimal mathematical efforts.

In an asynchronous pulsewidth modulation (PWM) method, the ratio of the carrier frequency to the fundamental frequency must be at least 15-20 in order to suppress the beat phenomenon. However, it is impossible to achieve this condition for large-capacity inverters (e.g., gate-turn-off thyristor inverters), when the fundamental frequency is high. Assuming that the beat phenomenon is caused by an error generated in the PWM process, we have introduced a compensator to reduce the error. As a result, beat phenomenon can be decreased for a low carrier frequency. Effectiveness of the proposed method is shown by experimental results. Index Terms - Beat phenomenon, gate-turn-off thyristor inverters, pulsewidth modulation, subharmonic method.

This paper describes a high-speed switching system for distribution networks which has been developed with the aim of improving power supply reliability (reducing the number of supply interruptions) of distribution systems. When a fault occurs in conventional distribution systems, the fault section is isolated using a sequential time-out control scheme which requires the reclosing and re-reclosing of the entire system. A major drawback of such systems is that normal sections are also subjected to unnecessary power supply interruptions. In order to resolve this problem, we have developed a high-speed switching system which isolates only the fault section without interrupting the power supply to normal sections. This new system can fully restore power to the normal sections and completely isolate the fault section within 500 ms in the case of a ground fault.

The study of the motion of moving metallic particles in GIS requires a good knowledge of the carried charge of the particle. In this paper measurements of the charging process of a moving particle, performed in a realistic one-phase GIS, are presented. By measuring the charge impulses and the voltage phase at consecutive impacts, it is possible to estimate the carried charge and then compare the results with the existing models of the particle charge. Also, besides the discharges from in-flight corona reported by several authors, it is shown that, for higher voltage levels, several discharges between the particle and the enclosure (outer electrode) can occur as the particle impacts with the enclosure. Keywords: Gas insulated switchgear, Particle Movement, Partial discharge detection, Diagnostics, Acoustic measurements