Effects of low earth orbit environments on atomic oxygen undercutting of spacecraft polymer films

Precise prediction on atomic oxygen undercutting by numerical simulation technique plays an importance role for long lifetime spacecraft design. A Monte Carlo mathematical model is presented to predict the undercutting process interaction between atomic oxygen and polyimide films of spacecraft in low earth orbital degree. In the meantime, the physical undercutting processes is described by tracing transportation particle approach on the basis of statistics. Simulated results showed that undercutting profiles with breaker patterns are in good agreement with flight experimental data for 43° and 28.5° orbit angle, as well as complicated effect factors are discussed in detail. Larger atomic oxygen fluence is favorable for producing more depth and width undercutting profiles and maximum depth is always larger than maximum width. Mass loss increased with the initial impact reaction probability increasing and decreased with the thermal assimilation coefficient going down. Especially for bigger orbit angle, the difference between depth and width are reduced due to the decrement of depth and the increment of width.