Electrostatic Discharge Threshold on Coverglass Used to Protect Solar Cells in the Low Earth Orbit

Coverglass has been widely used to cover the solar cells of solar arrays for space power generation. Coverglass with high antireflection is widely used to protect the solar arrays from performance deterioration due to irradiation of space ultraviolet, protons, electrons, atomic oxygen (AO), and so on. Along with these, thermal cycles and/or shock may accelerate the decay synergistically affecting the threshold voltage of electrostatic discharge (ESD) on the coverglass. In order to reveal the effect of aging due to AO interaction on the ESD threshold, several coverglass samples have been exposed to low earth orbit grade AO generated by the CO2 laser on the ground. Later, both pristine and AO-exposed coverglasses have been irradiated by energetic electrons to generate artificial arcing (ESD) under high vacuum system. Statistical analysis and Weibull distribution confirm that the threshold voltage of ESD is lower on the aged coverglass than virgin.