近年，高繰り返しパルスパワー発生源に関する回路技術と素子技術が急速に発展し，注目を集めている。各種高性能パルスパワー電源が開発され，加速器，環境，生物の分野で応用されはじめている。関連市場が広がりつつ，出力指標と製造コストとの間のバランスを極めるパルスパワー

Electrical characteristics of a silicon carbide (SiC)-MOSFET with the blocking voltage of 3.3 kV are evaluated, and an inductive energy storage (IES) pulsed power generator driven by the SiC-MOSFET is developed. The experiments are carried out using a circuit consisted of a capacitor and a resistor. The device temperature is controlled using a heater. The maximum pulsed current of 165 A with an input voltage of 80 V, the turn-on time of 31 ns and turn-off time of 22 ns are obtained at room temperature. The turn-on and turn-off times increase with the resistance of the evaluation circuit. On-resistance of 80 mΩ is obtained at room temperature and increases with the device temperature. IES pulsed power generator consists of a capacitor, a pulsed transformer and the SiC-MOSFET used as an opening switch. The maximum output of 9.8 kV and pulse width of 76 ns at the full-width-at-half-maximum are obtained with a charging voltage of 50 V and a charging time of 3 µs.

The virtual cathode oscillator (vircator) is one of the promising devices to oscillate high-power microwaves. Simplicity and high power capability are advantages. However, the low efficiency and frequency stability are serious problems. In this paper, we dealt double anode to strengthen the microwave interactions. The measurement result shows that the output of the virtual cathode oscillator can be progress by using the double-anode.

To understand the operation mode effects in a diagonal magnetohydrodynamic (MHD) accelerator, pulse width and direct current (DC) operations were numerically simulated. To evaluate the propulsion performance in a diagonal MHD accelerator, the incremental thrust, input power, and the ratio of thrust to input power were estimated using a one-dimensional numerical simulation. Pulse operation tend to improve the performance of the MHD accelerator compare to the DC operation. MHD acceleration performance increases when applying the optimum pulse width of discharge.

Oxidation of simulated soil using pulsed discharges is investigated. Glass beads are used as the simulated soil for evaluation of an oxidation ability of the discharges. Indigo carmine solution and Fusarium oxysporum are used to evaluate the oxidation ability, and are mixed with the glass beads. The moisture contents of the simulated soils with the indigo carmine solution and with the Fusarium oxysporum suspension are fixed at 9.1% and 16.7%, respectively. A plate to wire electrodes is used to generate discharges on the surface of the simulated soil. The high voltage pulses with voltage of 13 kV and pulse width of 250 ns are generated using a magnetic pulse compression circuit, and are applied to the wire electrode with pulse repetition rate of 2000 pps. The decolorization rate in the case of 16.7% is much lower than that of 9.1%. The deactivation effect of Fusarium oxysporum in case of 9.1% is higher than that of 16.7%.

Development and characteristic investigation of a pulsed radiation source which is generated by irradiating an electron beam to aluminum target was performed. An NaI(Tl) scintillation detector and a shaping amplifier were used for measuring the radiation energy. From the actual experiment, the radiation energy per unit area was estimated to be 12 MeV/mm² for one shot of electron beam irradiation. A CCD camera was used for estimating the radiation areal density. Number of white dots which considerable to effect caused by the radiation were existed in an acquired image. The areal density of white dots was obtained to be approximately 6000 dots/mm² at the behind of 3 m from the radiation source.

The purpose of this study is to propose an engineering ethics education for new electrical construction engineers. The contents of the proposed engineering ethics education are comprised of coping with the troubles assumed to be associated with four management aspects of construction which are “construction schedule management”, “cost management”, “quality management” and “safety management”. To put it concretely, through the case studies of dilemma caused by human relationships, the trainees learned the difficulty and importance of communication with focus on ethical considerations. Looking back on the training, they tried to ethically solve the troubles through dialogues. It is considered that the engineering ethics training during the new employee orientation is effective for developing the ethical awareness of the trainees because they can express the ethical principles in words by themselves. Furthermore, according to our research a half year later, we could confirm that the trainees recognized the necessity of the ethical thinking with a certain concrete image.

The environmental improvements by pulsed discharge plasma, a type of non-thermal plasma, have received much attention all over the world. The observation of discharge plasmas is beneficial for better understanding of the plasma physics of this growing field. Recently, nanosecond (ns) pulsed discharge with a short pulse duration of 5 ns achieved the higher energy efficiency on ozone generation and NO removal. However, the underlying mechanisms of these high efficiencies remain unclear. In the present study, the effects of electrode geometry on propagation process of ns pulsed discharge in coaxial electrodes were investigated using an ICCD camera. As the results, increasing wire diameters from 0.2 mm to 2.0 mm lead the different streamer discharge parameters; propagation velocity of streamer heads from 4.8 mm/ns to 12.5 mm/ns, peak of discharge current from 243 A to 328 A, respectively. Therefore, it is concluded that the wire diameter is one of the paramount parameters to control the characteristics of the ns pulsed streamer discharge.

Nonlinear resistivity of epoxy polymer composites containing ZnO particles and secondary particles was investigated. Epoxy composites containing ZnO particles are known to exhibit large nonlinear resistivity. These composites are composed of amorphous shaped ZnO surface-treated with silane (s-ZnO). Epoxy composites with 20 vol% s-ZnO including various concentrations of secondary particles were prepared. The effect of the secondary particles on the nonlinear resistivity of the epoxy composites was investigated. Measurement of the average particle-to-particle distance revealed that the average distance between s-ZnO particles was shortened by the addition of t-ZnO secondary particles. The average distance between s-ZnO particles affects the electric properties of the composite, i.e., the effect of t-ZnO as secondary particle addition on the nonlinear resistivity and electric breakdown field of epoxy composites containing s-ZnO was confirmed.

This paper describes an effect of transient electromagnetic fields (or pulsed electromagnetic fields) on the growth of radish. In our experiment, two kinds of transient electromagnetic fields by spark discharges were applied to seeds and seedlings of radish. In this experiment, the pulse widths of discharge current (800 A) were set to 3 µs and 15 µs, respectively. As a result, we found that the growth rates for the pulse width of 3 µs became greater than others (control [no application] and the pulse width of 15 µs) by around 23-38% especially when the temperature was high.