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The DC Surface Flashover Performance Research of Polyimide Under Low-Energy Electron Irradiation Environment

When a spacecraft is irradiated by electron in space, the surface flashover phenomenon on dielectric materials of a spacecraft can happen under the condition of lower dc voltage. In order to know the characteristics of surface flashover voltage on dielectric materials, we had a research about the dc surface flashover voltage of dielectric materials. In this paper, we prepared pure polyimide (PI) sample, and had surface flashover experiment for pure PI under dc voltage by low-energy electron irradiation. The results show that when electron energy is <;20 keV, the surface flashover voltage of PI in vacuum can increase with the increase in the electron energy; when the electron energy is more than 20 keV, the dc surface flashover voltage can decrease slightly with the increase in the electron energy. When the density range of electron beam is changing from 0.175 to 1.75 μA/cm2, the dc surface flashover voltage of PI sample has an exponential decrease with the increase in the electron energy density, and this phenomenon is more obvious with the increase in the electron energy density. Also, we discussed the mechanism preliminarily of that electron beam energy and electron beam density influence on the dc surface flashover voltage.