A report proposes that cylindrical asymmetrical capacitors (CACs) be used to generate small thrusts for precise maneuvering of spacecraft on long missions. The report notes that it has been known for decades that when high voltages are applied to CACs in air, thrusts are generated — most likely as a result of ionization of air molecules and acceleration of the ions by the high electric fields. The report goes on to discuss how to optimize the designs of CACs for operation as thrusters in outer space. Components that could be used to enable outer-space operation include a supply of gas and a shroud, partly surrounding a CAC, into which the gas would flow. Other elements of operation and design discussed in the report include variation of applied voltage and/or of gas flow to vary thrust, effects of CAC and shroud dimensions on thrust and weight, some representative electrode configurations, and several alternative designs, including one in which the basic CAC configuration would be modified into something shaped like a conventional rocket engine with converging/ diverging nozzle and an anode with gas feed in the space that, in a conventional rocket engine, would be the combustion chamber.

This work was done by Jonathan W. Campbell of Marshall Space Flight Center. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp  under the Electronics/Computers category.

This invention has been patented by NASA (U.S. Patent No. 6,775,123). Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to Sammy Nabors, MSFC Commercialization Assistance Lead, at This email address is being protected from spambots. You need JavaScript enabled to view it.. Refer to MFS- 31887-1.

NASA Tech Briefs Magazine

This article first appeared in the July, 2007 issue of NASA Tech Briefs Magazine.

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