Measurement of conductivity and charge storage in insulators related to spacecraft charging

Novel methods have been developed to measure conductivity and charge storage in thin film insulating spacecraft materials subjected to space radiations. For a variety of such samples, conductivity values differ by up to 10/sup 4/ from values based on ASTM standards. Conductivity and charge storage properties are found to be functions of prior radiation history. A highly-charged insulator emits electrons for hours (Malter Effect) after the irradiation beam is turned off. Visible light can be used to induce emission from previously charged samples with shallow traps.