The insulation characteristic of insulator in vacuum is researched in the process of the high voltage breakdown along the insulator surface in vacuum, which is called vacuum surface flashover.
绝缘子的真空表面绝缘特性研究真空下的高压沿绝缘子表面击穿物理过程，称真空表面闪络过程。
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High-voltage electric field combined with high temperature may lead to thermal breakdown and ageing of insulator for ESP.