A plasma propulsion engine is a type of Ion thruster which uses plasma in some or all parts of the thrust generation process. Though far less powerful than conventional rocket engines, plasma engines are able to operate at higher efficiencies and for longer periods of time. Plasma engines are better suited for long-distance Interplanetary space travel missions.
Plasma propulsion engines were first developed by the Soviet Union during 1963-1965 to propel spacecraft to Mars. In more recent years, many agencies have developed several forms of plasma fueled engines, including the European Space Agency, Iranian Space Agency and Australian National University, which have co-developed a more advanced type described as a double layer thruster.[1][2] However, this form of plasma engine is only one of many types.
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A Helicon Double Layer Thruster uses radio waves to create a plasma and a magnetic nozzle to focus and accelerate the plasma away from the rocket engine.
Magnetoplasmadynamic thrusters (MPD) uses the Lorentz force (a force resulting from the interaction between a magnetic field and an electric current) to generate thrust - The electric charge flowing through the plasma in the presence of a magnetic field causing the plasma to accelerate due to the generated magnetic force.
Hall effect thruster combine a strong localized static magnetic field perpendicular to the electric field created between an upstream anode and a downstream cathode called neutralizer, to create a "virtual cathode" (area of high electron density) at the exit of the device. This virtual cathode then attract the ion formed inside the thruster closer to the anode. Finally the accelerated ion beam is neutralized by some of the electrons emitted by the neutralizer.
Electrodeless plasma thrusters use the ponderomotive force which acts on any plasma or charged particle when under the influence of a strong electromagnetic energy gradient to accelerate the plasma.
Serial production started in Soviet Union in 1970s. One of the early variants, SPT-100 is now produced under license by European Snecma Moteurs under the name PPS-1350. SPT-290 has a thrust of 1.5N, 5-30kW power and specific impulse 30km/s, efficiency 65% and weight 23kg.
VASIMR, or Variable Specific Impulse Magnetoplasma Rocket, works by using radio waves to ionize a propellant into a plasma and then a magnetic field to accelerate the plasma out of the back of the rocket engine to generate thrust. The VASIMR is currently being developed by the private company Ad Astra Rocket Company, headquartered in Houston, TX with of help from a NS Canada based company Nautel, producing the 200kW RF generators for ionizing propellant. Some of the components and "Plasma Shoots" experiments are tested in a laboratory settled in Liberia, Costa Rica. This project is led by former NASA astronaut Dr. Franklin Chang-Díaz (CRC-USA). Recently the Costa Rican Aerospace Alliance announced the cooperation to this project by developing an exterior support device for the VASIMR to be fitted in the exterior of the International Space Station, as part of the plan to test the VASIMR in space, this test phase is now expected to be conducted in 2014. The VF-200 engine could reduce the duration of flight from Earth to say Jupiter or Saturn from six years to fourteen months, and Mars from 4 months to 39 days.