Surface flashover propagation process on alumina dielectrics under impulse voltage application in vacuum

We investigated the mechanism of surface flashover on alumina dielectrics under impulse voltage application in vacuum in order to enhance the electrical insulation performance of vacuum insulated power equipment. Through electrical and optical simultaneous measurements, we discussed propagation process of the surface flashover on alumina dielectrics in vacuum. We changed the incident angle (θ) of electric lines of force to the alumina surface, i.e. parallel and perpendicular as the main parameter. The different propagation process of the surface flashover was found and discussed by the difference of charging process due to an electron flight distance.