Degradation of gas switch insulator due to electrode erosion

In the electrode erosion process, melted and evaporated metal removed from electrode surface may contaminate the gas switch insulator and increase the probability of flashover accident, influencing the lifetime of gas switch and the stability of pulsed power system. In this paper, researches on the degradation of morphology and insulating strength of insulator surface were carried out while PMMA and brass were employed as the insulator and electrode material respectively. The results show that the electrode erosion would generate plenty of metal vapors and ejected droplets. The metal vapors would congeal and produce tiny metal powder covering the insulator, meanwhile, the ejected droplets would bombard the insulator and generate dense cracks and embed metal particles. After 300 shots, the leak current of insulator surface increased and the flashover electric field decreased, on the other hand, the surface insulation resistance in different regions had a great distinction, resulting in an uneven distribution of electric field. As a result, the flashover voltage decreased and the probability of flashover accident increased.