Investigations into Synergistic Effects of Atomic Oxygen and Vacuum Ultraviolet

Polymer materials exposed to a space environment exhibit strongly degraded properties because or environmental factors, for example, atomic oxygen, vacuum ultraviolet, and radiation. In addition, the degradation of polymer materials can he accelerated because of the synergistic effects of these environmental factors. For designing high-reliability-spacecraft, it is important to understand precisely the polymer materials' degradation. In this report, the synergistic effects of atomic oxygen and vacuum ultraviolet on polyimide-films, Kapton H, and silver-coated fluorinated ethylene propylene films were investigated through comparison of the degradation behaviors after single, sequential, and simultaneous irradiations. For both materials, there was no significant change attributed to the synergistic effects in erosion yield and thermo-optical properties. However, the surface morphology of silver-coated fluorinated ethylene propylene changed substantially depending on the irradiation method. Surfaces of silver-coated fluorinated ethylene propylene were eroded by atomic oxygen, but were smoothed by vacuum ultraviolet. The surface morphology after sequential irradiations differed depending on irradiation sequence. A rougher surface with low blunt cones; was produced after simultaneous irradiation because of the interaction of the erosion by atomic oxygen attacks and smoothing by vacuum ultraviolet irradiation. This report also describes the measurement methods for fluence of each beam under simultaneous irradiation.