Surface flashover properties of alumina ceramics modified by ion implantation

Surface flashover across the insulators in vacuum is the major limitation of the performance of the high power system. Surface characteristics of Insulator effect its surface flashover performance obviously, appropriate surface treatment can increase the surface flashover voltage. Ion implantation technology is an effective surface modification tool, it can change the roughness, resistivity and adsorbability on the insulator surface. Alumina ceramics are used widely in vacuum insulation system. In this paper, Alumina Ceramics were modified by nitrogen ion and carbon ion, nitrogen ion was produced by a electron cyclotron resonance (ECR) ion source, carbon ion was produced by a metal vapor vacuum arc (MEVVA) ion source. The surface flashover voltage were measured on the experimental platforms of surface characteristics in vacuum before and after modification, also the surface topography was studied by using the microscope. In order to find the influencing factors on surface flashover properties of alumina ceramics modified by ion implantation, the simulations on ion implantation was completed by using SRIM software. The experimental results show the ion implantation can improve the surface flashover voltage in vacuum. When the incident angle is 90°, the modification effect is best. The 50% and continuous flashover voltage in vacuum had a inflection point when the implanted energy of nitrogen ion beam changed. When the energy of ion implantation is 80keV, the flashover voltage can increase about 50% with the electrode distance of 5mm and the specimen size of 52mm×24mm×7mm under vacuum 1.5×10^-4 Pa. The mechanism of surface flashover properties modified by ion implantation was discussed.