We have developed a macro model that focuses only on electrical characteristics to handle the discharge phenomenon as a circuit. We considered the discharge as a kind of non-equilibrium system and modeled the transient changes in the discharge impedance. We also examined how to fix these model parameters from measurable values. We applied it to the high frequency dielectric barrier discharge and obtain sufficient agreement with the measurement results. We think that this model can be applied, not only to discharge phenomena but also as a method for circuit-modeling a general physical phenomenon in which the state changes transiently in a non-equilibrium system.

Plasma generated in xylene by an application of bipolar pulsed voltage is used to synthesize nano-carbon materials. Characteristics of the synthesized materials such as structure, surface area, and pore diameter are evaluated for various discharge conditions. The synthesized carbon consists of spherical primary particles with sizes ranging from 20 to 50 nm which has a randomly stacked lattice structure with aliphatic chains. Although the structure is not dependent on voltage parameters, surface area decreases with increasing frequency while voltage amplitude and pulse width have less effect. When plasma is generated with high speed solvent flow accompanied by generation of cavitation bubbles, tubular structure in synthesized materials is observed in addition to the spherical particles. Fast transportation of radicals from the plasma reaction field may change the synthesis mechanism of carbon materials.

Lightning observation system was developed by measuring the current flowing through the grounding conductor connected to the foot of the Mt. Fuji from the summit. From the current measurement, the type of lightning and leader was identified such as negative cloud-to-ground lightning striking into the weather station, upward leader lightning, and stepped leader. The paper showed the mechanism of these current generation. It was found that the observation system was an effective measuring system for lightning including leader and the electrostatic due to the thunderstorm approach.

Measurements of the first and second ionization coefficients α and γ_T in He/H₂O (95.4 ppm) mixture are carried out using a steady state Townsend method. Observed ionized multiplication currents are analyzed by Nakamura's plot to determine both of the ionization coefficients. The obtained first ionization coefficient in the mixture is large compared with those of helium and water molecule in the range of the reduced electric field E/N≦1131 Td (E/p₀≦400 V/cm Torr) affected by Penning ionization between the metastable excited He atoms and H₂O molecules.
Therefore, it is validated that the Penning ionization is formed in the mixture and the related behaviors of the metastable excited He atoms He(2³S₁) and He(2¹S₀) are also discussed in this paper.

Green juice is attracting attention as a health food, but since it is a freshly squeezed juice of young barley leaves, it contains soil-derived bacteria. When heat is applied for sterilization, chlorophyll and enzymes in green juice are inactivated, the color deteriorates, and nutrients decrease. Therefore, we are trying to apply pulsed electric field sterilization, but since green juice has high conductivity, a large amount of conductive current flows between the electrodes, which causes temperature rise due to Joule heat and dissipation of the electrodes. Therefore, we have developed a rotary electrode that suppresses the temperature rise of green juice and electrode dissipation caused by Joule heat.

Several studies for partial discharge (PD) pattern recognition using artificial neural network (ANN) were reported in the early 1990s. Usually, in an actual field such as a substation, data on partial discharge is scarcely available, or even rare. In many cases, the power supply phase required for the PRPD pattern cannot be easily obtained. We propose an ANN method that shifts the phase in which the maximum signal intensity detected with PD sensors is generated and used it as training and input data, even for the few phases resolved PD data available in the field. This ANN method was applied to the PRPD pattern obtained in a practical field. As a result, it was shown that the discrimination rate between PD and noise was improved, and therefore the proposed ANN method was found to be effective.

For the hard coating field, we have developed a new physical vapor deposition (PVD) technology for one-piece coating of rod parts, a magnetron sputtering device in which a cylindrical target surrounds the substrate. TiN films formed under HiPIMS and DCMS drive of the device using cylindrical Ti target were compared. It was shown that a high-hardness and dense TiN film, which is characteristic of the HiPIMS method, can be formed using the prototype substrate surrounding type magnetron sputtering device.

With the activation of the lunar manned exploration plan, a power device that can be driven with high efficiency is required for effective utilization of electric power resources. On the ground, the development of nanocomposite materials in which nano-sized fillers are added to epoxy resin is being developed for semiconductor encapsulation materials and inverter module cases. These materials are expected to be applied to the development of lunar rover, and further improvement of the dielectric strength of the materials is required. Therefore, this time, we focused on the secondary electron emission yield (SEEY), which is the electrical property value, and measured for the nano-silica added epoxy resin when it was subjected to high temperature treatment, and whether it could be applied to a semi-empirical model formula. We report on the fact that we have examined the above.

Previously, the pulsed electroacoustic method could not separate the true charge and the polarization charge at the sample-electrode interface. This is because the positional resolution of the measurement device is not sufficient. In this study, we attempted to separate the true charge and the polarization charge by applying a pulse voltage and a DC voltage to the sample through an air gap. The polarization charge is formed by dielectric polarization, so the permittivity can be calculated by measuring the amount of the polarization charge. Therefore, in this paper, we measured the polarization charge of polymeric insulating materials with different relative permittivity when applying step voltage as an initial study. As a result, it was observed that the charge signal reflected the polarization charge at the sample-air interface. Consequently, it was suggested that the PEA method enables to measure the permittivity while observing the charge distribution inside the sample.

An alternative testing method applicable to both air discharge and contact discharge is proposed via a fixed gap from an ESD generator in its contact discharge mode under conditions limited to a test voltage of 8 kV. The method can be used not only to provide the air discharge current close to the step response of the ESD generator through a fixed gap from 0.03 mm to 0.5 mm, but also via 1 mm gap to give the contact discharge current that meets IEC calibration requirements.

Based on numerical and experimental analyses of sound pressure distributions owing to partial discharges in oil-immersed transformer, we propose an effective arrangement of acoustic emission sensors. The sensor arrangement at the surface edge of the transformer housing allows us to minimize the required time for diagnosing.