The effect of anode on the initial stage of a vacuum discharge

The insulation capability is a key indicator for designing a vacuum interrupter. A vacuum discharging process, especially the initial stage of it, is correlated to the capability. However, the effect of anode is still uncertain in a vacuum discharge process. The objective of this paper is to experimentally investigate the effect of anode on the initial stage of a vacuum discharge. A ICCD camera was adopted to observed the radiance from a vacuum discharge. According to the results, a vacuum discharge was initiated at the cathode. The cathode light was restricted in a small region in the process of a discharge. However, the anode radiance, appearing 250 ns after the light emitted from the cathode tip, expanded towards the cathode, bridging the gap. It means that the anode has an important effect in supplying vapour for the construction of a conducting channel between the electrodes at the initial stage of a vacuum discharge.