Vacuum Ultraviolet Radiation Characterization of RF Air Plasma and Effects on Polymer Films

Abstract

Radio-frequency (RF) plasma ashers have been extensively used in atomic oxygen (AO) durability screening of candidate spacecraft materials. Because RF excitation/deexcitation of a gas produces ultraviolet radiation, samples exposed to AO in the plasma asher are also exposed to ultraviolet radiation. In an effort to quantify the vacuum ultraviolet environment in the asher, this paper will describe measurements of the intensity of vacuum ultraviolet (VUV) radiation over the 115–200 nm wavelength range for a plasma asher operated on a feed gas of room air. Measurements were made in narrow bands (9–27 nm) within the 115–200 nm range and for the full 115–200 nm range. VUV intensity in the asher was compared to space solar intensity in the same wavelength ranges. Preliminary tests were conducted to examine the use of the asher as a VUV source while examining general VUV degradation trends for common polymer materials. Mechanical properties of polymer films of Kapton® HN, Teflon® FEP, Tefzel® ZN, Mylar®, and polyethylene were evaluated as a function of asher VUV exposure. For these tests, samples were wrapped in aluminum foil with the gage area visible under magnesium fluoride windows in an effort to protect them from atomic oxygen while still allowing VUV radiation of wavelengths down to 115 nm to reach the samples.KeywordsVacuum UltravioletSample AssemblyGage AreaNASA Glenn ResearchPlasma AshersThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.