ELECTRICAL BREAKDOWN OF VACUUM INSULATION AT CRYOGENIC TEMPERATURE

A breakdown experiment of vacuum insulation for the development of cryocables and other cryogenic electrical apparatus was performed. The influence of conditioning, pressure, gap spacing, electrode material and voltage waveshape on the breakdown voltage of vacuum insulation was measured at room temperature and at cryogenic temperature respectively. The results indicated that cooling the HV sphere electrode enhances the breakdown strength of vacuum insulation, and in general, almost all effects of electrical breakdown of vacuum insulation at room temperature are reproduced at cryogenic temperature at somewhat higher voltage, the close correlation between the low-temperature and room-temperature breakdown voltages of large vacuum gaps can be explained from the point of view of microparticle-initiated breakdown theory. © 1990 IEEE