Glow discharges have been used in gas lasers and the plasma processing. However, it is difficult to sustain a stable glow discharge at a high input electric power. One of methods to sustain the stable glow discharges is to use the gas flow. The phenomena of glow discharges in the gas flow are not understood clearly.
In this paper, the characteristics of glow discharge for a point-to-plane gap in the gas flow are investigated. The point electrode is the hemispherically ended electrode of 0.5mm in radius, and the gap length is 10mm in the nitrogen of several hundred Torr. The light emission from the glow discharge in the gas flow seems to spread, and waveforms of the current and voltage are oscillatory. It is found from the detail measurements of the discharge that the gas flow prevents to sustain the stable glow discharge and produces discharges which repeat the glow discharge and the discharge just before the transition to the glow discharge. In the positive point-to-plane gap, the discharge current just before the transition to the glow discharge is pulsative. In the negative point-to-plane gap, the discharge current is pulseless. The difference of the discharge just before the transition to the glow discharge in one of reasons why characteristics of the discharge in the gas flow change by the polarity.

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The authors investigated the partial discharge characteristics of SF₆ gas wedge gap against the AC and the impulse voltages. It was clarified that the impulse partial discharge voltage (impulse PDIV) is higher than the AC partial discharge voltage (AC PDIV). The ratio of impulse PDIV to AC PDIV is 1.5-1.8 for lightning impulse or 1.4-1.8 for switching impulse.
We calculated the breakdown voltage of gas wedge gap provided that gas wedge gap satisfies Pashen's Law, and compared it with the experimental results. As a result, the AC PDIV has very good agreement with the calculated breakdown voltage in low gas pressure, but in high gas pressure the AC PDIV is lower than the calculated value. On the contrary, impulse PDIV is higher than the calculated value in all experimented gas pressure range,
It is clarified that these phenomena is explained by the lack of initial electrons in gas wedge gap in low gas pressure and by the residual charge in gas wedge gap in addition to the lack of initial electrons in higher pressure.

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Breakdown phenomena of insulating materials have been studied by many investigators. In a previous paper, thermally stimulated current of an LDPE film under non-uniform electric field was measured by using the needle-plane electrode system. Then, we analyzed the space charge characteristics of the film.
In the present paper, thermally stimulated surface potential built up in an LDPE film under non-uniform electric field was measured using the same needle-plane electrode system as in the previous paper. Then we estimated both the range, wherein the space charge field is formed, and the electric field formed at the tip of needle electrode by the space charge. Finally, we concluded from the theoretical analysis that we can obtain the space charge characteristics of insulating materials, e. g. space charge field, by using the experimental results of TSSP measurement and that of TSC measurement.

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Various molecular weight measuring methods of insulating oil have been proposed from long ago. At present, method of Hirschler is well known. This method is obtained from the temperature dependence of viscosity, and is used frequently to measure ring analysis of insulating oil or lubricating oil. However, this method is hard to obtain the molecular weight.
So, here is studied about easy measuring method of the molecular weight. As a result, following equation was obtained from compensation low and the temperature dependence of viscosity, M=0.053ln(η/0.0036)/(1/RT-0.001), where M is the molecular weight (g/mol), η is the viscosity (Poise), R is 1.987cal/mol•deg, T is the temperature (K).
By modifing the equation, the molecular weight calculating equation was obtained from the density at 15°C, d₁₅(g/cm³) and the kinematic viscosity at 40°C, ν₄₀(cSt) in Japanese Industrial
Standerd tests of insulating oils as follows, M=87.2ln(2.73d₁₅ν₄₀).
In this study, further, temperature dependence equation of viscosity was deduced by using compensation low.

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