Light Emission Characteristics before Flashover along Surface of Polymer under AC Voltage in Vacuum
Zhang Guanjun¹, Yang Minzhong¹, Yan Zhang¹, Liu Yuanxing², Ishii Shozo²
(1. Xi'an Jiaotong University , Xi'an  710049 , China; 2. Tokyo Institute of Technology)

Abstract: Examined is the initiation mechanism of flashover along the surface of polytetrafluoroethylene (PTFE) under AC voltage in vacuum. Two distinct phases of light emission were observed,i.e.,a stable low-level optical process under low voltage,so-called phase A,and an irregularly intense process called phase B for a lightly higher voltage.The results suggest that phase A is due to electroluminescence (EL) produced by the recombination of electrons and holes injected from electrodes. A new model has been proposed to explain the optical phenomena in phase B and the developing process of surface flashover.
Keywords: polytetrafluoroethylene;surface flashover;electroluminescence;partial discharge