Spectroscopic Study of Surface Flashover Under Pulsed Voltage in Vacuum

Surface flashover has already become a limiting factor in pulsed power systems, and a thorough understanding of its mechanism is fundamental to improve it. Since optical diagnostic methods can provide more information for understanding the flashover mechanism than electrical ones, in this paper the light emitted during surface flashover along polytetrafluoroethene (PTFE) was diagnosed by a spectrograph together with an intensified charge-coupled device, and the spectrum of laser-induced breakdown of PTFE was also recorded as a comparison. The results show that the spectrum of laser-induced breakdown is composed of line spectra emitted by material elements. While many band spectra emerge in the spectrum of surface flashover besides the former line spectra, which implies that the source of flashover plasma includes desorbed surface gases as well as vaporized insulator material. This result also reveals a more detailed picture of the flashover process.