Electric Discharge Pulses in Irradiated Solid Dielectrics in Space

Electric charging and discharging phenomena on spacecraft are reviewed. Laboratory tests of spacecraft materials, performed over the last six years by many workers, are summarized. A conceptual framework is proposed to explain the apparently diverse findings and to guide future studies: prebreakdown events (microdischarges) appear to produce small Lichtenberg trees with a plasma which conducts large current under certain conditions. An extensive set of measured pulse data in several polymers is compared to theoretical prediction of radiation induced internal electric fields which rise as high as 2×106 V/cm due to trapped irradiation spacecharge alone. Implications for spacecraft are discussed.