Single-pulsed surface flashover voltage of the electrode geometry in vacuum

Abstract

Single-pulsed surface flashover voltage of insulator can be considerably improved by reasonable design of electrode geometry. In the present work, the electric field distribution of cylindrical alumina insulators with different electrodes is simulated. Simulation results indicate that amendatory geometries could reduce electric field strength of the cathode-triple-junction(CTJ) and the ratio of electric field component parallel (F‖) to an insulating plane with the normal component (F⊥). The theoretically deduction demonstrates that the energy of the first electron collision can be reduced by decreasing the ratio of electric field (F‖/F⊥). Several electrodes are designed and manufactured, and surface flashover voltages of cylindrical alumina insulators are measured in vacuum in different electrodes using ~3μs singlepulsed. As a result, the reliable voltage hold-off of the screening electrode B is up to 150 kV and nearly 50% higher than that of the plate electrode. The measurements show good qualitative agreement with the behavior from the computation. Consequently, studies on the pulsed voltage holdoff property of the electrode geometry in vacuum could be quite helpful in designing of the insulating geometry for high voltage vacuum devices.