Surface Electric Field Analysis of Insulating Material with Transitional Permittivity in Vacuum

Surface flashover in vacuum is a kind of important physical phenomena. Considerable work has been done on the effects of insulating material on its surface flashover characteristics, i.e. the dielectric permittivity, conductivity, surface roughness, surface trap distribution and so on. For general insulator material, its permittivity is constant, which brings many disadvantages. On the condition of keeping a good contact between electrode and insulator, if the insulator can be layered with different permittivity, with higher permittivity at the region near each electrode and lower permittivity far away from electrode, the local field at the triple junction (the proximity of metal electrode, insulator and vacuum) will be greatly reduced. This paper assumes the insulator piled up by a lot of slices, the permittivity of those slices is transitional along the surface between cathode and anode. Five kinds of feasible variation patterns are employed and the electric field distribution of each pattern are analyzed and discussed in detail