The electrodeless plasma thruster is a spacecraft propulsion engine commercialized under the acronym "E-IMPAcT" for "Electrodeless-Ionization Magnetized Ponderomotive Acceleration Thruster". It was created by Mr. Gregory Emsellem based on technology developed by French Atomic Energy Commission scientist Dr Richard Geller and Dr. Terenzio Consoli, for high speed plasma beam production.
This thruster technology can deliver large thrust density as the acceleration process is not limited by plasma density through Hall Parameter or grid electrical screening. Further, as the ponderomotive force accelerates all plasma species in the same direction, this thruster technology does not need any neutralizer. The fact that electrodeless plasma thruster is inherently multi-staged allows it to optimize both stages independently, or to throttle the thruster at constant power between higher specific impulse and higher thrust. The field of ponderomotive force is created by a non-uniform high frequency field and static magnetic field, thus it implies no grids nor contact between the plasma and any electrodes, hence it avoids most thruster erosion and spacecraft contamination issues.
Propulsion systems based on electrodeless plasma thrusters seem ideally suited for orbit raising for large geostationary satellites, and would also be able to perform orbital stationkeeping, hence enabling important propellant mass savings. The ability of this technology to provide large thrust density also allows faster missions to the outer planets.
The use of ponderomotive force to accelerate a plasma has recently been investigated from a theoretical point of view by Princeton Plasma Physics Laboratory scientists I. Y. Dodin, Y. Raitses and N. J. Fisch. 
Some theoretical research has also been reported around the debated issue of the existence of a double layer in such a thruster, even if such a double layer structure would be current-free, as both ions and electrons travel in the same direction at the same average terminal speed. The existence of current free double layer is still debated among plasma physicists.