Surface flashover across ceramic disks in vacuum at cryogenic temperatures

As superconducting technology becomes more viable in the marketplace, especially in high power applications, the need for a well researched high thermal conductivity electrical insulator is needed. The electrical failure mode for these types of insulators is often surface flashover at sub-atmospheric temperature and pressure. Testing of two such insulators, aluminum nitride and aluminum oxide, for this failure mode is done for two differing surrounding electrode geometries. The testing shows an increasing breakdown voltage trend with decreasing temperature. These results indicate a temperature related dependence of the secondary electron emission and electron induced outgassing that is a component in the process of surface flashover. The research also covers the effect of electrode conditioning, and presents optical diagnostics of the gas species involved during breakdown.