Simulation of space charge behavior in polyethylene under blade-plate electrode system

Electrical tree is well known as an initial cause of breakdown, and it's believed to be highly related to the movement of injected charges. This paper presents a simulation of space charge behavior under highly non-uniform electrical field generated in blade-plate electrode system. A numerical analysis model using finite element method has been carried out, based on bipolar charge transport model. The trapping, detrapping and recombination of charges are decided by Poisson's equation, the conservation law. The boundary condition were given by the Schottky injection law. In order to obtain a more accurate electrical field around the blade, an edge refinement mesh obeying normal distribution has been used. It is shown that the non-uniform electrical field is flatted greatly due to space charge injection and trapping. And the charge injected by blade electrode is the main source of space charge inside the material, the movement of charges from one electrode to another has similarity with the growth of electrical tree.