Study on electric insulation properties for development of conduction-cooled HTS SMES Original Research Article

The conduction-cooled HTS SMES magnet is operated in high vacuum and cryogenic condition. Thus, electric insulation design at high vacuum and cryogenic temperature is a key and important element that should be established to accomplish compact design that is a big advantage of HTS SMES. However, the performance of insulators under cryogenic conditions in air or vacuum is virtually unknown. Therefore, we need active research and development of insulation concerning application of the conduction-cooled HTS SMES. Specially, this paper will present the results of high vacuum and cryogenic temperature breakdown and flashover discharge characteristics between cryocooler and magnet-coil. The breakdown and surface flashover discharge characteristics are studied at cryogenic temperature and vacuum. Also, some materials such as aluminum nitride (AlN), Al2O3 that have high thermal conduction are taken up and the flashover discharge characteristics are investigated. From the results, we confirmed that basic database on the discharge between cryocooler and magnet-coil was established for the electric insulation design.