Internal Dielectric Charging Simulation of a Complex Structure With Different Shielding Thicknesses

To find the real risk points of internal dielectric charging (IDC), 3-D IDC simulation is performed to a typical dielectric structure considering GEO severe radiation environment (FLUMIC3). Charge transportation simulation is carried out by Geant4 and electric field is numerically computed according to the current conservation law. The aluminum shielding thickness is varied to investigate the shielding dependence. By adjusting the lower energy limit of the incident electron spectrum according to the shielding thickness, a technique is proposed to improve the simulation efficiency. The statistic condition in Geant4 is checked and attention is paid to the influence of mesh on the peak electric field. The simulation data show that the peak electric field occurs on the grounding edge and local mesh refinement on the critical charging point is of significance to make sure the real charging level. Increasing the shielding thickness could mitigate IDC. However, this mitigation effect is weak in the case where radiation-induced conductivity dominates the total conductivity (at low temperature). In this case, even using a 3-mm aluminum shielding, the peak electric field can reach the level of 10⁷ V/m.