|Budget Amount *help
¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 1988: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1987: ¥3,500,000 (Direct Cost: ¥3,500,000)
Mechanism of gas discharge at cryogenic temperature is known as almost same as that at room temperature in uniform field for DC and AC voltage. In non-uniform field, however, many kinds of phenomena which are different from those at room temperature have been observed and investigated in this project.
1. Negative discharge in nitrogen gas varies continuously from corona to glow. The transition voltage does not change at cryogenic temperature and shows some higher value at room temperature, probably because of aqueous vapor.
2. Negative discharge in air is not affected by temperaturechange, when the gas density is kept constant.
3. The positive flashover voltage in nitrogen gas increases more for the lowere temperature, when the tip of needle electrode is sharp. However, the increasing rate becomes smaller, when the equivalent radius of needle tip becomes larger. For the radius of larger than 2mm, the flashover volttage does not change by temperature.
4. The positive flashover voltage in air is not influenced by temperature for a sharp needle. For the needle whose tip has an equivalent radius of larger than than 0.5mm. the positive flashover voltage in air decreases at low temperature.
These results will have more importance, if super-conductive materials will be used at higher temperature, where nitrogen is vaporized.