Influence of Charge Injection on Dynamic Characteristics of Space Charge in Polymer Thin Films Under AC Stress

At present, most studies focused on the formation and accumulation of space charge under DC stress, relatively few studies focused on dynamic characteristics of space charge under AC stress. However, space charge dynamics under AC stress is of significance because the majorities of polymer insulation systems are subjected to AC voltage. In order to study the effect of charge injection mechanism from the electrodes on dynamic characteristics of space charge under AC stress, bipolar charge transport model are used to simulate the current density, electroluminescence intensity, space charge densities in polyethylene with different charge injection mechanisms. It is found that the simulated electroluminescence intensity and space charge densities under AC stress assuming the exponential functional approximation injection is more reasonable than those assuming the Schottky injection.