The accumulation characteristics for surface charge on the insulator under nanosecond pulse voltage in vacuum

The electric field could be distorted by the accumulated surface charge on the insulator, even flashover voltage could be decreased. In vacuum, the flashover voltage of the insulator is much lower than both insulator's materials and the vacuum gap in the same dimension. In order to enhance the flashover voltage under nanosecond pulse voltage in vacuum, it is very important to take the study of the distribution of the surface charge of the insulator. A set of insulator surface charge measurement system under nanosecond pulse in vacuum has been set up in this paper. This paper adopts the electrostatic capacitance probe method to acquire the distribution of surface charge of the different samples, and compares the characteristics of surface charge accumulation among different samples. The results indicate that there is obviously charge accumulated on the surface of sample without additive, while on the surface of sample mixed with additive there is no charge accumulated or the charge accumulation amount is less than the probe sensitivity. Comparing the charge accumulation amount of all samples under three pulses to that under one pulse, there is an obvious increase.