Current leakage for low altitude satellites

Abstract

Ionospheric plasma densities exceeding 1,000,000 per cu cm exist around satellites in low earth orbit. Operation of large solar arrays at high voltage may drive substantial leakage currents through this surrounding plasma. Power losses exceeding solar cell output have been observed for small arrays biased above +2,000 V. Estimates of these effects for very large power systems are developed. Recent large scale (10 meter) lab tests are reported. Estimates based on calculations of space charge limited sheath dimensions are identified as a good working model, leading to projected power losses for large arrays increasing much more slowly than for small arrays.