Improving surface flashover performance in vacuum through co-firing Mo/Al2O3 cermets and Al2O3 ceramics

Some insulating structures of Mo/Al₂O₃ cermet - Al₂O₃ ceramic - Mo/Al₂O₃ cermet were prepared to improve surface flashover performance in vacuum through co-firing, where the volume amount of Mo was managed from 2 to 50 vol% and there could exist one or two layers with different Mo amount in Mo/Al₂O₃ cermet. The influences of Mo amount of Mo/Al₂O₃ cermet on the surface flashover voltage in vacuum of samples were experimentally investigated, indicating that the surface flashover voltage of three and five-layer structures were improved by 77% and 117%, respectively. Through the electrostatic field simulation, it was found that the improvement is caused by the weakening of the electric field at vacuum-insulator-cathode triple junction.