Validation through Experiment and Simulation of Internal Charging–Discharging Characteristics of Polyimide under High-Energy Electron Radiation

Abstract

Due to the injection of energetic particles, such as electrons in space environment, the internal charging–discharging characteristics of spacecraft dielectrics need to be evaluated for the safety of spacecraft, and the evaluation results from experiments and simulations should be comparatively validated. An in-site pulsed electroacoustic (PEA) measurement system under high-energy electron radiation was established for evaluating the charging characteristics of thick plate samples about 3 mm, while a joint simulation method based on Geant4 and COMSOL was also proposed. The deposited charge distributions were compared through experiment and joint simulation method under 0.7, 1.0 and 1.3 MeV for 30 min and 1.0 MeV for 10, 60 and 120 min, respectively. Meanwhile, the electrostatic discharging characteristics were also comparative evaluated by both methods under 0.3 MeV for 20 min under 5, 10 and 15 µA beam current, and the total discharging times and initial discharging time were compared and analyzed. Overall, a good consistency existed between experimental and simulation results of charging–discharging characteristics under electron radiation while the difference was also analyzed in the perspective of dielectric properties, such as charge leakage by conduction. Through the comparative study, both evaluation methods are validated, which offers effective reference for the safety evaluation of spacecraft dielectrics in future.