Vacuum surface flashover on insulator of long-pulse diode

During the experimental study of a long-pulse intense-current foilless diode, surface flashover along its insulator was observed. The analysis of the phenomenon shows that, too short distance between the shield ring and insulator resulted in an intense electric field at the edge of the shield ring, which leaded to the emission of electrons; with effect of intense electromagnetic field, the electrons came into collision with the surface of the insulator, causing secondary electron emission avalanche, and then resulted in vacuum surface flashover. The structure of the shield ring was improved by use of electrostatic field simulation and particle simulation. The improved diode, whose voltage and current are respectively 600 kV and 10 kA, works steadily with guiding magnetic field of 1 T. Vacu