EROSION OF KAPTON H BY HYPERTHERMAL ATOMIC OXYGEN: DEPENDENCE ON O-ATOM FLUENCE AND SURFACE TEMPERATURE

Abstract

Organic polymers are susceptible to erosion from reaction with ambient atomic oxygen in low Earth orbit. We have investigated the linearity of the O-atom fluence dependence of Kapton H erosion and the dependence of Kapton H erosion yield on surface temperature. Sample exposures were performed with a pulsed beam containing hyperthermal O atoms that were generated with a laser detonation source. After exposure, samples were removed from the chamber in which the exposures were done, and postexposure analyses were performed: etch depth (profilometry) and surface topography (atomic force microscopy). A systematic set of exposures, which eroded room-temperature Kapton H from 1.4 to 25 μm, showed that the erosion yield of Kapton H is linearly dependent on O-atom fluence. This result helps validate the use of KaptonHmass loss (or erosion depth) as a linear measure of the O-atom fluence of a materials exposure. The erosion of Kapton H was strongly temperature dependent. At lower temperatures (<100°C), the erosion yield appeared to be independent of sample temperature. But above 100°C, the erosion yield exhibited an Arrhenius-like temperature dependence, with an apparent activation energy of 0.31 eV. These observations suggest that O-atom-induced erosion of Kapton H proceeds through direct, nonthermal, gassurface reactions, and through reactions that depend on the surface temperature.