Pulsed plasma thruster
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Pulsed plasma thrusters are a method of spacecraft propulsion which use an arc of electric current adjacent to a solid propellant (almost always teflon), to produce a quick and repeatable burst of impulse. PPTs are great for attitude control, and for main propulsion on particularly small spacecraft with a surplus of electricity (those in the hundred-kilogram or less category). However they are also one of the least efficient electric propulsion systems, with a thrust efficiency of less than 10%.
Pulsed plasma thrusters were the first electric propulsion system to be deployed in space, on the Soviet probes Zond-2 in 1964 and Zond-3 in 1965. Used as an experimental system for spacecraft orientation control, Soviet engineers subsequently returned to the use of high-pressure nitrogen jets.
Pulsed plasma thrusters were flown in November, 2000 as a flight experiment on the NASA Goddard Space Flight Center EO-1 spacecraft. The thrusters successfully demonstrated the ability to perform roll control on the spacecraft and also demonstrated that the electromagnetic interference from the pulsed plasma did not affect other spacecraft systems.
See also: Hall effect thruster, Magnetoplasmadynamic thruster, Spacecraft propulsion, Magnetic sail
