The electric field analysis of A-B-A insulators in vacuum

In this paper, A-B-A insulators were designed to improve the characteristics of surface flashover in vacuum by adjusting conductivity and permittivity of layer A. According to electric field theory of series dielectrics, the DC and pulsed field distributions of the insulators were calculated and the influences of conductivity and permittivity of Layer A on the electric field of vacuum-insulator-cathode triple junction and vacuum-layer A-layer B triple junction of A-B-A insulators were analyzed. It is found that by controlling the conductivity and permittivity of Layer A, the electric field of vacuum-insulator-cathode triple junction can effectively recede while the one of vacuum-layer A-layer B triple junction can be kept away from a high value. Then with the consideration of dielectric surface electrification, we analyzed the impact of layer A with different polar charges on its surface on the electric field of vacuum-insulator-cathode triple junction and vacuum-layer A-layer B triple junction. At last, we estimated the trend of surface flashover voltage in vacuum of A-B-A insulators under the condition of a continuous change of conductivity or permittivity of layer A.