Low-energy electron exposure effects on the optical properties of ZnO/K_2SiO_3 thermal control coating

摘要

An experimental investigation was undertaken to study low-energy electron exposure effects upon ZnO/K_2SiO_3 thermal control coating. The specimens were exposed to 10-, 30-, 50-, and 70-keV electrons, respectively. The spectral reflectance of each specimen was measured in situ before and after electron exposures. The solar absorptance was calculated by assuming a Johnson solar spectral irradiance distribution. Electron paramagnetic resonance and photoluminescence measurements were made before and after electron exposures to explain physical changes induced by the electron exposures. All the specimens exhibited a reflectance decrease throughout the visible and the near-infrared regions, and also the induced optical degradation was found to be electron energy dependent, with increased damage for increasing electron energy. It is believed that the optical degradation of ZnO/K_2SiO_3 thermal control coating, induced by the low-energy electron exposures, is mainly due to the ionization process of the ZnO pigment.