Optical characterization of condensed and photofixed RTV effluent

摘要

Room Temperature Vulcanized (RTV) materials, such as silicone adhesives, are commonly used to bond components of communication satellites and other types of spacecraft. The elevated satellite operating temperature causes the unused catalyst material in the RTV to volatize, which can then re-deposit or condense onto other spacecraft surfaces. In the presence of sunlight, this Volatile Condensable Material (VCM) can photo-chemically deposit onto optically-sensitive spacecraft surfaces and significantly alter their original, beginning-of-life (BOL) optical properties, such as solar absorptance and emittance, causing unintended performance loss of the spacecraft. Knowledge of the optical impact of photo-chemically-deposited VCMs is therefore a major concern of spacecraft designers and spacecraft-contamination engineers. In view of this we have employed in-situ spectroscopic ellipsometry to monitor in real time the optical constants of the condensed effluent of RTV CV-566 and CV-2568 as well the photofixed effluent of CV-566. This technique is sensitive to nm thick layers and can be used to extract n and A: as a function of wavelength. We will present the optical constants, n and k, for both condensed unexposed and the photofixed film.