Ionospheric plasma current collection properties of pinholes-results from the SAMPIE Experiment

Summary form only given. Ionospheric plasma current measurements to spacecraft materials, measured by the NASA Solar Array Module Plasma Interaction Experiment, are presented. Insulated copper disks were prepared, with pinholes in the insulation. The pinholes were several mils in diameter. The copper was biased over a range of -300 to 300 volts, and the current from the plasma was measured. Frequently, this current shows a sharp increase at higher voltage, referred to as snapover. In this paper, comparisons of theoretical predictions of current collection to experimental measurements are presented. Implications for snapover in spacecraft are discussed.