Microscopic and macroscopic material properties effects on ultraviolet-laser-induced flashover of angled insulators in vacuum

Flashover of electrically stressed polymeric insulators in vacuum has been induced by ultraviolet radiation from an excimer laser (KrF). The authors present the results of an experiment which (1) quantifies the effects of ultraviolet illumination on polymeric insulators; (2) characterizes ultraviolet-induced flashover over insulators at positive and negative angles, and (3) correlates microscopic and macroscopic material properties to flashover behavior. A theory of ultraviolet-induced insulator flashover is developed, which explains the unexpected variation of flashover strength with geometry in view of the current understanding of flashover in vacuum.>