Vacuum Surface Flashover Induced by Load Current in Pulsed Power Facilities

Surface flashover of vacuum insulator is one of the key factors limiting the performance of pulsed power facilities. Based on a typical pulsed power facility, the flashover characteristics of its insulator in the presence of load current are studied. It was found that the flashover always occurred after the voltage reversal, namely after the first current peak when using an inductive load. Single particle motion analysis was carried out according to the secondary electrons avalanche model, and it was pointed out that the magnetic field generated by the load current will accelerate or inhibit the development of secondary electrons avalanche, changing the flashover voltage significantly. Under the action of applied voltage with different polarity, the effect of magnetic field on flashover voltage is opposite. The time and position of the flashover in open-circuit and short-circuit experiments was compared, which provided direct experimental evidences for the effect of load current on the insulator flashover.