科研之友
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摘要
A Monte Carlo model describing the interaction between atomic oxygen undercutting with polyimide Kapton film of spacecraft surfaces in low earth orbit is presented. The physical process of atomic oxygen undercutting is elaborated and a binary chained list optimization technique is used to reduce computations. In order to analyze the impact-reaction probability in three-dimensional space, a new mathematical impact-reaction probability based on the mapping theory is established to be the important reaction parameter for predicting the difference of undercutting patterns between two-dimensional and three-dimensional spaces. Numerical simulations are carried out with different initial defect widths, orbit inclination angles, thermal assimilation-reaction coefficients and thickness of protective layers, as well as their combining action conditions. Results agree well with the NASA long duration exposure facility experimental data. The maximum undercutting depth is larger than the maximum undercutting width at all times, which reduces with increase in orbit inclination angle, thermal assimilation-reaction coefficient, three-dimensional space and thickness of the protective layer. Comparing three- and two-dimensional spaces, the maximum depth is decreased by approximately 20% for 28.5 degrees orbit inclination angle.
