GEANT4 Simulation of Interplanetary Proton Induced Deep Dielectric Charging

Abstract

Energetic protons with high fluence are a major reason for internal charging of dielectrics in interplanetary spacecraft. In this paper, the proton induced internal charging of dielectrics is predicted based on radiation induced conductivity (RIC) model and particle transfer software package GEANT4. With GEANT4-RIC simulation, the fluence and dose depth profiles in Kapton and Teflon under 10 MeV proton radiation are obtained. These results are introduced into the RIC model containing the current continuity equation, the Poisson equation and the trapped charge equation to solve the internal charge and electric field distributions. The latter is compared with insulation disruption field as a guideline for discharging behavior.The performed simulations validated a common experimental result that discharge occurs in Kapton after it was irradiated with protons at a fluence of 3 × 1012/cm2 and Teflon does not exhibit such phenomena. The obtained results confirm that the GEANT4-RIC method can be used to evaluate the proton induced dielectric charging and that it provides a basis to understand better the interplanetary proton induced internal charging problem.