Investigations into Synergistic Effects of Atomic Oxygen and Vacuum Ultraviolet

Polymermaterials exposed to a space environment exhibit strongly degraded properties because of environmental factors, for example, atomic oxygen, vacuum ultraviolet, and radiation. In addition, the degradation of polymer materials can be accelerated because of the synergistic effects of these environmental factors. For designing highreliability 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 propylenefilmswere 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 irradiationmethod. 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 the 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.