The Effect of PD Process on the Accumulation of Surface Charges

The distribution of surface charges at the interface between gas and insulating material relates to the partial discharge process in a void. In order to clarify this, a 2-D model is constructed in this paper. Based on this, the streamer development and the accumulating process of surface charges are obtained under both polarities of the applied voltage. It is found that the maximum surface charge density appears at the middle location of the interface, and monotonically decreases along the radial direction. As the drift velocity of the electron is higher than that of the positive ion, the accumulation of surface charges takes a much shorter time under the negative voltage than under the positive. Besides, the effect of the applied voltage amplitude and the void height on surface charge distribution is obtained. As the applied voltage or the void height becomes greater, the discharge process becomes more intense, leading to an increase of surface charge density and surface charge distribution area.