- a type of rocket engine in which thrust is obtained by the electrostatic acceleration of charged positive ionsCompare plasma engine
- A rocket engine that develops thrust by expelling ions fired by an electron gun, used in some spacecraft. Though ion engines create less thrust than chemical combustion engines, they are considerably more efficient and require very little propellant, resulting in much lighter weight and less need for high thrust. See also solar-electric propulsion.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.