DISPOSITION OF SPS ELECTRIC THRUSTER EXHAUST D. H. HOLZE AND H. B. LI EMOHN BOEING AEROSPACE COMPANY SEATTLE, WA 98124 Presented at the DOE/NASA Satellite Power System Program Review April 22-25, 1980 University of Nebraska - Lincoln The transit of large Space Power System vehicles from low earth orbit to geosynchronous altitude requires electric thruster propulsion that will deposit great quantities of ions into the magnetosphere. Interactions between this foreign material and the natural environment needs study in order to assess possible modifications of communication paths, auroral illumination levels, and radiation dosage to spacecraft. Methodology has been developed for determining the temporal and spatial distribution of the exhaust ions (probably A+) from the Orbit Transfer Vehicles (OTVs). The analysis takes account of large angles between the thrust vector and the OTV velocity (nearly orthogonal) which are required to reach the equatorial plane. Consequently, the dense plume of thruster ions is seldom normal to the earth's field, as frequently suggested. After the initial expansion, individual ions follow (Van Allen type) trapped trajectories in the geomagnetic field. The principal loss mechanism is charge exchange with natural oxygen and hydrogen. Preliminary quantitative estimates indicate only a fraction of the exhaust ions re-enter the atmosphere, most escape.
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