纳秒脉冲下真空绝缘沿面闪络特性实验研究

Investigation of Flashover Characteristics Under Nanosecond Pulse in Vacuum

通过实验研究了纳秒脉冲（10／30ns）T，真空绝缘沿面闪络电压随圆台形绝缘体锥角、圆柱形绝缘体截面直径、实验气压以及电极材料等物理因素的变化趋势，结果表明圆台形绝缘体锥角变化对闪络电压影响非常明显;厚度相同的圆柱形绝缘体闪络电压随截面直径的增大而降低，且直径越小，变化幅度越大；当气压处于高真空范围，即10^-5～10^-1Pa时，气压变化对闪络电压不构成影响;高真空条件下不同电极材料对闪络电压无影响。并在系统分析实验结果的基础上，提出了真空绝缘结构设计原则。

Dependence of Flashover Voltage on cone angle of conical frustum, diameter of cylindrical insulator, gas pressure and electrode material has been experimented in high vacuum （10^-5～ 10^-1 Pa） under 10/30-nanosecond pulse power. It has been shown experimentally that cone angle has much effect on flashover voltage, and flashover voltage of 45o conical frustum is the highest. Surface flashover voltage of ±45° conical frustum under short pulse waveform is much higher than that of cylindrical insulators, and the amplitude of flashover voltage for dc and power frequency ac voltages is lower. Electric field in CTJ （cathode triple junction） of 45° conical frustum is lowest; flashover voltages decrease with the diameter of the insulator, and the reason for reduction is because the increasing length of the triple junction provides more relatively weak points for the initiation of surface flashover; flashover voltage is independent of the gas pressure under high vacuum, and flashover is in fact a type of gaseous discharge in a high-pressure phenomenon immediately above the insulator surface. There is no appreciable difference in flashover voltages for different electrode materials. According to experimental data and mechanism analysis, several suggestions are recommended regarding how to design an insulator used in vacuum circumstance.