Measurement of 2-Dimensional Surface Charge Distributions under Vacuum Flashover Events on Insulators with Sub-milli-second temporal resolution

Abstract

Most studies on a flashover event in vacuum has revealed that the surface charging on insulator has a great influence on the flashover. However, regarding most studies related to the surface charging, their measurements were carried out after high voltage excitation. In this research, the measurement of 2-dimensional surface charge distributions in real time has been carried out in vacuum by Pockels effect. With this measuring method, the charge distributions on a dielectric sample can be measured from the high voltage application to the surface flashover event. This paper describes the changes of the surface charge distributions on a PET film under non-uniform ac voltage application in vacuum. Moreover, using this method, the charge distribution just before and after a surface discharge event on the PET film has been measured. Especially we focus on the distribution near the triple junction just before and after the surface discharge event.