Solar array drive mechanism（SADM） is a crucial component of the electrical transfer subsystem of long life and large power satellite

which is sensitive to the detrimental effects of internal charging and discharging. In order to test the influence of in-space charging effects on the polyimide dielectric of SADM

we proposed and verified a project to experimentally investigate the impact of impurity and geometry on internal charging and discharging properties of polyimide.An electron accelerator was utilized to carry out 2 Me V electron beams irradiation test on samples of different impurities and structures. The surface charging potential and electrostatic discharge were monitored during three kinds of conditions. It is indicated that the charging potential is positively correlated with the height of polyimide rib. But the influence of width of polyimide rib on the charging potential varies with different impurities. The most significant impact on charging potential is the nonlinear conductivity generated by doping modification of polyimide. In general

proper choice of impurity and design of structure would minimize internal charging and discharging threat to SADM.