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An ion thruster, ion drive, or ion engine is a form of electric propulsion used for spacecraft propulsion. An ion thruster creates a cloud of positive ions from a neutral gas by ionizing it to extract some electrons from its atoms. The ions are then accelerated using electricity to create thrust.
6 kW Hall thruster in operation at the NASA Jet Propulsion Laboratory. In spacecraft propulsion, a Hall-effect thruster (HET) is a type of ion thruster in which the propellant is accelerated by an electric field. Hall-effect thrusters (based on the discovery by Edwin Hall) are sometimes referred to as Hall thrusters or Hall-current thrusters.
The gridded ion thruster is a common design for ion thrusters, ... Despite the demonstration in the 1960s and 70s, though, they were rarely used before the late 1990s.
The NEXT thruster has demonstrated, in ground tests, a total impulse of 17 MN·s; which as of 2010 was the highest total impulse ever demonstrated by an ion thruster. [2] A beam extraction area 1.6 times that of NSTAR allows higher thruster input power while maintaining low voltages and ion current densities, thus maintaining thruster longevity.
A 4-grid ion thruster with only 0.2 m diameter is projected to absorb 250 kW power. With that energy input rate, the thruster could produce a thrust of 2.5 N . The specific impulse (a measure of fuel efficiency ), could reach 19,300 s at an exhaust velocity of 210 km/s if xenon propellant was used. [ 3 ]
The Deep Space 1 and Dawn used the NSTAR, a solar-powered electrostatic ion propulsion engine. The NASA Solar Technology Application Readiness (NSTAR) is a type of spacecraft ion thruster called electrostatic ion thruster. [1] [2] It is a highly efficient low-thrust spacecraft propulsion running on electrical power generated by solar arrays.
Field emission electric propulsion (FEEP) is an electrostatic propulsion method based on field ionization of a liquid metal, and subsequent acceleration of the ions by a strong electric field. Sharp features such as needles are used to enhance and concentrate the strength of this electric field.
The chosen orbital altitude is a trade-off between the average thrust needed to counter-act the air drag and the impulse needed to send payloads and people to the station. GOCE which orbited at 255 km (later reduced to 235 km) used ion thrusters to provide up to 20 mN of thrust to compensate for the drag on its frontal area of about 1 m 2 .