Breakdown electron temperature in spark gap switch by high voltage pulses

Summary form only given. SF₆ gas is known as an effective insulator due to its high dielectric characteristics. Because of this property, it is widely used in the field of high voltage pulse systems and compact electrical distribution sites. But the phenomenon of breakdown between spark gaps according to SF₆ ratio and mixture gas pressure is still unknown well. There are several parameters about breakdown phenomenon between the spark gap switches. Electron temperature is one of most important parameter in plasma. We have investigated the electron temperature according to the SF₆ rate and pressure. We used the high power microwave generator named, “Chundoong”, which is a high-power pulse generator with maximum 600 kV, 88 kA, and 60 ns pulse duration. We installed the breakdown chamber in front of vacuum chamber. The material of electrode is copper-tungsten consisting of 70 % tungsten and 30 % copper. We have used nitrogen gas (N₂), sulphur hexafluoride (SF₆) and there mixture gases, respectively. The SF₆ has been mixed from 1 % to 30 % to the N₂ basis. Mixture pressure has been changed by 100 torr, 400 torr, 1 atm, 2 atm, 3 atm, and 4 atm. It is found that the electron temperatures are rapidly increased to 10 %, but beyond that those are saturated to be 17 eV. These electron temperatures above 10% mixture ratio of SF₆ are not in big differences in accordance with gas pressures in this experiment.