Analysis of primary electron supply process and suppression of primary electron in high pressure nitrogen

Nitrogen molecule has some metastable states and they accumulate energy for long period. The activated species generated by the former discharges supply primary electron which leads to breakdown in the space. Therefore, the activated species affected the breakdown voltage or the breakdown probability when the voltage is applied repeatedly. It is assumed that primary electron is supplied by the contribution of N atom or nitrogen metastable molecules. By the way, recombination reaction of N atom depends on cathode surface area and cathode material. Accordingly, we changed the cathode surface area or the cathode material to analyze the primary electron supply processes in high pressure nitrogen gas. Delay time of breakdown was measured. The results showed that surface area was increased. In addition, primary electron number in case of Au electrode increased more than that of W and Mo. From these results, it is concluded that surface process on the electrode, for example recombination reaction of N atom, contributes dominantly to supply primary electrons.