Interaction potential between atomic oxygen and polymer surfaces in Low Earth Orbit

In the present work, an interaction potential between an incident reactive particle and a. material surface is constructed. The potential is formulated based on the unit bond index-quadratic exponential potential model and two adjustable factors characterizing the correlations of equilibrium-length scales and of attractive potential. In addition, the effective potential between monomers is obtained by Lifshitz's theory. The interaction of atomic oxygen with Kapton(R) is computed as a test case using the potential functions developed in the present paper in conjunction with the molecular dynamic model constructed by Lee and Chen (Lee, C.-H., and Chen, L. W., "Reactive Probability of Atomic Oxygen with Material Surfaces in Low Earth Orbit," Journal of Spacecraft and Rockets, Vol. 37, No. 2, 2000, pp. 252-256). The reactive probability computed by the present model is found to be 16.8% lower than for the STS-46 flight data, and the law of the incident angle-dependency deduced from the flight data is also confirmed by the numerical simulation. The numerical value of the accommodation factor computed in this task is 0.1368, which lies between the values of 0.1165, computed via the hard-sphere model, and 0.68, obtained from the ground test for atomic oxygen interacting with Kapton at an impingement angle of 45 deg and energy of 1.5 eV. The effects of the two adjustable factors given in. the potential model are also briefly discussed.