DC surface flashover characteristics on polyimide under different temperature in vacuum

Researching the effects on different temperature of dc surface flashover characteristics on solid insulating dielectric in vacuum what can improve the reliability applied to complex environments. In this paper, we use the self-made polyimide (PI) sample as the object of study. The dc surface flashover characteristics at different temperatures (193-353K) are experimental studied, with theoretical analysis. It is found that the dc surface flashover voltage presented first decreased and then increased and finally decreased again with the increasing of temperature. The dc flashover voltage reached the maximum at 313K and minimum at 273K respectively. The experiments suggest that the electron emission near the cathode, the charge transport of dielectric insulators and the gas desorption are important reasons for the affecting of PI material dc flashover voltage as the temperature increased. Besides, the characteristics of the material itself also has important effects when the temperature varied.