Environmentally Induced Discharges in a Solar Array

In the continuing effort to simulate discharges seen during geomagnetic substorms, the charging and discharging characteristics of an electrically isolated solar array segment are being studied. A solar array segment is floated while bombarded with monoenergetic electrons at various angles of incidence. The potentials of the array surface and of the interconnects are monitored using Trek voltage probes, to maintain electrical isolation. A back plate is capacitively coupled to the array to provide information on the transients accompanying the discharges. Several modes of discharging of the array were observed at relatively low differential and absolute potentials (a few kilovolts). A relatively slow discharge response in the array was observed discharging over one second, with currents of nanoamps. Single faster discharges were also seen which lasted a few tenths of a millisecond and with currents on the order of microamps.