Influence of Flashover Initiation Process on Surface Insulation Performance for Insulators under Impulse Voltage in Vacuum

This study experimentally presents how the flashover evolves from cathode-initiated to anode-initiated. An intensified CCD camera was employed to capture the surface flashover development process across 95% alumina ceramics in vacuum under seven kinds of electrode-sample structures with different electric field distributions. Experiments results suggested that flashover could initiate at either cathode or anode, which strongly depended on the competition between the localized field stress and electrical strength of the material. A basic relationship between surface flashover development process and its insulation performance was established. This study may contribute to guide the design of facilities used for pulsed power and electro-vacuum fields to achieve higher insulation capability.