低能质子辐照下F46/Ag光学性能退化及损伤模型

利用空间综合辐照环境模拟器对F46/Ag二次表面镜进行低能质子辐照试验,发现30 keV质子辐照会导致F46/Ag的光学性能发生显著退化,波长为350 nm处的光谱反射率变化值随累积辐照通量呈指数关系增加,太阳吸收比变化值随累积辐照通量线性增加。通过Monte Carlo模拟计算得到不同深度电离能损和位移能损的分布,发现质子辐照F46/Ag主要通过电离进行能量的传递。当质子能量为30 keV时,F46表面获得质子传递能量的最大值。量子化学计算结果表明30 keV质子辐照F46/Ag时材料表面C—F键和C—C键断裂所需吸收的能量远小于质子传递给F46表面的能量。XPS分析表明质子辐照后材料表层发生了一系列断键和重组反应,生成了自由基和分子片段,表面发生脱氟和碳富集,与量子化学计算结果相吻合。

Optical degradation and damage model of F46/Ag under low-energy proton irradiation

The low-energy proton irradiation test on the F46/Ag second surface mirrors was performed in a ground-based space irradiation environment simulator. The results demonstrate that the 30 keV proton irradiation can lead to a significant degradation of the optical properties. The changes of the solar absorptance increase linearly with the fluence and the changes of the reflectance at the 350 nm wavelength increase exponentially with the fluence. The distributions of the ionization and the non-ionizing energy loss in different depths are acquired by the Monte Carlo method. It is found that the energy is transferred from protons to atoms of the F46 mainly through ionization during the irradiation and the surface layer absorbs the most energy under 30 keV proton irradiation. The quantum chemistry calculation indicates that the 30 keV proton irradiation can induce the debonding of C-F and C-C in the surface layer and the energy required in the bond breaking reactions is much less than that of the protons transferred to the F46 molecules. The XPS results show that the proton irradiation induces several debonding and recombination reactions in the surface layer, leading to the formation of free radicals and molecule fragments as well as the decrease of F and surpluses of C, as in agreement with the quantum chemistry calculation.