Research on Simulation of Deep Charging for Spacecraft Dielectrics

Based on Monte Carlo simulation and Radiation-Induced Conductivity (RIC) model of charging dynamics, a new predicting method aiming at spacecraft dielectrics deep charging is brought forward to calculate charging density and internal electric field and is also validated by ground tests. The charging model of dielectrics is simplified as a compound structure consisting of shielding aluminum and multiple-layer plates in Geant 4. The injected current density and dose rate profiles of Teflon along depth are statistically accumulated and normalized with practical flux density. Then substituting these results into RIC model, the distributions of charging density and electric field in Teflon under the condition of backside grounded are numerically calculated. Finally, the profiles of space charging density in Teflon under various injecting electron fluxes are measured by Pulse Electro-Acoustic method (PEA). Numerical and ground tests show that charging density and electric field increase while the injected electron flux is enhanced for Teflon radiated by 100 keV electron. The peak of charging density is about 0.042 mm and the maximum electric field is closed to the grounded side. With universal characteristics of Geant 4 particles transfer simulation and RIC model, the predicting method is suitable for various spacecraft dielectrics.