Resistance Jet Microthruster System Development

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Resistance Jet Microthruster System Development

W. N. Neiman

This report is a summary of the work performed in the design, fabrication, and test of resistance jet microthruster systems for East-West station keeping and station changing duties on the Dodge-II Satellite. The thrusters were electrically heated and ammonia gas was used as fuel. For the station keeping function, thrust values of 3, 6, and 9 micropounds were supplied. For station keeping, 100 micropounds of thrust were provided, with a catalyst being used to assist in decomposition of the ammonia. Included in this work was the design and fabrication of a torsion-wire device that was used for measuring thrust in the required low range. Parabolic flights of KC-135 aircraft carrying plastic models of the microthruster system's fuel tank proved its suitability for delivering gas to the propulsion system under zero-g conditions. These experiments, showing equilibrium positions of the propellant, were recorded in slow motion on a 900 foot reel of color film. Electrical designs were completed for a power and signal conditioner to convert satellite electrical power into the forms required by the microthruster system. A portion of this conditioner contained circuitry to condition the various instrumentation signals into a form acceptable to the vehicle telemetry system for earth transmission. (Author)