航天器介质深层充电模拟研究

针对航天器介质深层充电问题,提出了一种基于蒙特卡罗模拟和充电动力学RIC模型的介质电荷分布及电场预估新方法,利用地面试验验证了其正确性.航天器介质平板充电过程被简化为屏蔽铝板与分层介质组成的Geant 4模型,通过统计方法计算出了实际入射束流下Teflon介质内的注入电流密度和剂量率分布曲线,利用RIC模型获得了背面接地时介质中的电荷密度和电场分布,利用脉冲电声法(PEA)对不同束流密度辐照下的Teflon内部空间电荷密度进行了测量.数值模拟和地面试验结果表明,Teflon在100 keV能量电子辐照下,电荷密度和电场随着束流密度的增加而不断增大,其电荷密度峰值位置约为0.042 mm,且背面接地时接地侧电场最大.由于Geant 4粒子输运模拟和RIC模型具有通用性,因此该方法适用于各种航天器介质材料.

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.