Electroluminescence and degradation in PE caused by electron impact

Degradation and electroluminescence is observed in the initiation stage of electrical tree before partial discharge starts. Two mechanisms had been proposed for these phenomena; one is electron impact model; electron injected from electrode are accelerated in micro void and/or polymer free volume and causes bond scission and excitation of chromophores (light emitting center). The other model is recombination between electron and hole emits light, and uv component of light degrade polymer. We examined effect of gas or liquid in polymer free volume/micro void on EL and degradation, and found that contents of free volume/micro void have a large effect on both. The results show both of EL and degradation is caused by electron impact.