Investigation of electrostatic discharges during irradiation of elements of thermal control coatings of spacecraft radiators

This study analyzes the characteristics of electrostatic discharges occurring on the surface of K-208 glasses irradiated in a vacuum of $10^{-4}$~Pa by electrons with an energy of 40 keV at a particle flux density of $3\cdot 10^{10}$~cm$^{-2}$~s$^{-1}$ and varying the fluences from $10^{14}$ to $10^{16}$~cm$^{-2}$. Discharges of type 1 and type 2 with plasma ejection into the surrounding space were observed when the glasses were irradiated. The frequency of discharges increased and the amplitude of discharge currents decreased when the fluences were varied from $10^{14}$ to $10^{16}$~cm$^{-2}$. This is explained by the increase of glass electric conductivity caused by the change of stoichiometry and structure of the material during discharges. Along with electrostatic discharges, there are also breakdowns on the irradiated surface of the sample to the metal subsurface material of glass K-208. Under certain conditions, these processes may stimulate each other, that is, an electrostatic discharge may provoke a breakdown and vice versa.