Role of UV radiation in pulsed flashover along vacuum-epoxy/nano TiO2 composite interface

This paper aimed at clarifying the effect of UV illumination on the pulsed vacuum flashover of TiO₂ (titania)/epoxy nano composites. Vacuum surface flashover voltage under pulsed voltage, thermally stimulated depolarization current (TSDC) and photoelectrical current were investigated. It was found that flashover voltage of all the samples was decreased by UV illumination. Flashover voltage reduction of neat epoxy is the smallest, and that of nano composite increases with the decrease of filler content. The degradation of flashover voltage is congruous with the amount of shallow-like traps but has no evident correlation with total amount of traps, whereas photoelectrical current is mainly affected by total amount of traps. As a result, it was clarified that UV radiation in flashover can improve both the electron emission and charge neutralization through affecting the charging and discharging process of traps. Moreover, the effect of UV radiation on shallow-like traps is dominant in the flashover process.