Influence of Electrode Geometry on Pulsed Surface Flashover of the Alumina Insulator in Vacuum

Research on the surface flashover of the vacuum insulation under pulsed voltage is significant for the design and manufacture of pulsed power devices. In this paper, several new electrodes are designed and manufactured, and the surface flashover voltages of the cylindrical alumina insulators are measured in vacuum in different electrodes using a single pulse. The influence of the depth of the metal of the recessed electrode on the withstand voltage of the gap is reported in detail. We find that a screening electrode could increase the relative hold-off voltage almost 50% more than a plane electrode could. The developing process of surface flashover in vacuum by microsecond pulses is also discussed. Consequently, studies on the pulsed voltage hold-off property of the electrode geometry in vacuum could be quite helpful in designing the insulating geometry for high-voltage vacuum devices.