Research on the Breakdown Process of Needle-Shaped Electrode Switch in Air

Through the needle-shaped air gap switch, self-breakdown characteristics of calorific and luminescent properties tested in the air depict that before the onset of discharge, the calorific effect corresponding to the cathode is more pronounced than the anode. There were positive and negative bipolar corona discharges before the onset of switch breakdown. The temperature at the tip of the electrodes was maximum at the discharging moment, and the luminescence occurred in the anode prior to the cathode before the onset of switch breakdown. The relationship between the spark breakdown voltage and the gap length could be approximated as linear. The experimental results confirmed that these phenomena were the consequence of the differences between the conditions for the development of avalanches and streamers, taking place between the cathode and anode electrode, respectively.