Influence of Pulse Steepness on Vacuum Flashover of Casting Epoxy Resin

Research on the pulsed flashover characteristics of vacuum insulation material is significant for the design and manufacture of pulse power devices. In view of the voltage increase rate of the fast pulse (pulse steepness), the vacuum flashover characteristics of pure epoxy under different steepnesses is investigated by using a pulse generator with parameters of a rise time of 40 ns and a full width at half maximum of 2.5 μs. Pulses with six levels of steepness were achieved by changing the charging voltage of the generator. Based on the linear equation and electron emission equation, the relationship between the flashover voltage and pulse steepness was fitted. By virtue of the fitted formula, it was possible to predict the flashover voltage under near DC or higher steepness conditions. Based on the electron emission equation, the relationship between the time delay and flashover field was also fitted. Result shows that F-N electron emission dominates the flashover process. (fusion engineering)