行星际空间质子引起介质深层充电的GEANT4模拟研究

Geant4 Simulation of Interplanetary Proton Induced Deep Dielectrics Charging

高通量的空间质子是导致行星际航天器深层充电的主要原因,基于辐射诱导电导率模型(RIC)和粒子输运模拟工具GEANT4对介质材料在质子辐照条件下的深层充电问题进行了预估。利用GEANT4-RIC充电计算方法,首先计算出10MeV质子在Kapton和Teflon中的注量和剂量沉积曲线,进而根据电流连续性方程、泊松方程和电荷俘获方程组成的辐射诱导电导率模型(RIC)求解出介质内电荷和电场分布,与介质击穿电场阈值对比作为其是否发生放电的依据。模拟结果证实了对10MeV质子,在质子注量为3×1012/cm2时Kapton会发生放电,而Te-flon则不会发生放电的一般性试验结论。验证了GEANT4-RIC方法用于行星际航天器介质材料质子充放电评价的可行性,为此类问题的解决奠定了基础。

Energetic protons with high fluence is a major reason causing internal dielectrics charging in interplanetary spacecraft, thus the proton induced internal charging problem of dielectrics is predicted based on radiation induced conductivity （RIC） model and particle transfer soft package GEANT4 in the paper. With GEANT4 - RIC simulation, fluence and dose profiles along with depth in Kapton and Teflon under 10MeV proton radiation are obtained, then these results is introduced into the RIC model consisting of current continuous equation, Poisson equation and charge trapped equation to solve internal charge and electric field distributions, and the latter is compared with insulation disruption field as a guideline for discharging or not. The simulations validate a common experimentation result that Kapton occurs discharge after radiated with the fluence of 3×10^12/cm^2 and Teflon does not give such a phenomena. It proves that above GEANT4 - RIC method can be used to evaluate the proton induced dielectric charging and provides a basis to interplanetary proton induced internal charging problem.