The influence of the UV-intensity on IF-filter protected second surface mirror alpha sub s stabilities, including surfaces with conductive top layers

摘要

To retard the commonly experienced degradation of the solar absorption coefficient of SSM and OSR, several protective thin film coatings were applied to Teflon FEP SSM and Suprasil glass OSR. Both substrate materials were chosen because of their superior stability under solar radiation exposure, compared to other plastics and glasses. The performance of these protected substrates was evaluated in terms of their solar absorption changes under accelerated solar radiation test conditions, with 7,5 solar constants (SK), 3,5 SK, and 2 SK. Several sets of samples were exposed to UV radiation only, and to UV and proton radiation simultaneously. A few samples were coated with a thin layer of In2O3 to study their surface resistance during the course of simulated solar radiation exposure. Results indicate, that it is possible to maintain within the error limits a constant solar absorption coefficient of IF filter protected SSM and OSR over an exposure time of 3000 ESH.