Surface flashover characteristics of polyimide during electron beam irradiation under DC voltage in vacuum

In order to enhance the reliability of polyimide (PI) in complex engineering environments, we obtained the characteristics of surface flashover on polyimide under DC voltage in vacuum during electron beam irradiation through experiments. Besides, trap parameters of the tested samples before and after radiation were also measured using the thermally stimulated current (TSC) method. The results show that, the surface flashover voltage of sample under the radiation with electron energy of 0.5~20 keV is higher than that under no radiation. Higher electron energy leads to smaller positive charge density on dielectric surface and smaller relative dielectric constant, as well as larger trap, and consequently improves the uniformity of surface electric field and increases the flashover voltage. If the radiation electron energy remains the same, the flashover voltage would become lower with increasing beam density, number of initial electrons and leakage current.