Numerical Simulation Of Atomic Oxygen Erosion Process Of Surface Material In Low Earth Orbit Using DSMC Method

In low Earth orbit (LEO) from 200 to 700 km a harsh space environment including hazards such as atomic oxygen, UV radiation, high vacuum, micrometeoroids and debris, as well as severe temperature cycles can cause considerable damage to vulnerable spacecraft surface materials. Atomic oxygen (AO) is more predominant of these environmental factors. Ground laboratory exposure test and numerical simulation are conducted to investigate interaction between atomic oxygen and Kapton which is frequently used in this paper.Recurring to the results of LDEF about atomic oxygen erosion of Kapton by NASA, the paper suggested the basic hypothesis of undercutting model. The program to numerically simulate the process of atomic oxygen effect was developed using DSMC approach and compiled using FORTRAN language. Inosculation of results of numerical simulation and results of exposure experiment in space and in plasma asher proved that the undercutting model is feasible and precise.Numerical simulation focused on the influences of AO quantities, defect size, thickness of protective coating, and angle from normal incidence since these factors had critical influences on atomic oxygen erosion of Kapton. The depth of atomic oxygen undercut cavity increases with the atomic oxygen fluence increasing, but shows a slight change with a much larger fluence. The width of atomic oxygen undercut cavity varies with the thickness of the protective coatings, and the depth of undercut cavity also exhibits a small change. The configuration of atomic oxygen undercut cavity is different with different defect sizes. The wider defect has more flat undercut cavity, which is wider at the bottom than at the top. When the angle of attack relative to normal incidence (ANI) grows, the ratio of the atomic oxygen entering the cavity falls of and the undercut cavity tilts. All results agree well with the undercutting model. In summary, the numerical simulation results can provide a useful guide to develop new materials and protective coatings for aerospace application.