Degradation of solar absorptivity of thermo-optical materials contaminated by electric propulsion

One of the objectives of this work was to contaminate samples by the erosion of different targets in order to study the effect of this contamination on their thermo-optical properties. The second objective was to validate the Spacecraft Plasma Interaction System (SPIS) module dedicated to simulation of erosion and contamination. First, experiments were conducted in IDEFIXe chamber at ONERA to expose OSR and SSM to contamination created by the erosion of targets representing elements of a spacecraft using electric propulsion, subject to ions bombardment. The targets were submitted to Xe+ ions beam. Samples were placed facing the target and were then submitted to the contamination by erosion products. The quantity of contaminants was estimated through a quartz micro-balance. Reflectance of the contaminated samples was then measured to evaluate the effect on their solar absorptance and their surface was characterized by XPS. Different targets and different samples were used allowing us to extract general tendencies and phenomenology. In a second time, simulations of the test were performed with SPIS. These simulations have allowed us reproducing experimental results, validating the code and proposing erosion mechanisms for polymeric materials.