New thruster design increases efficiency for future spaceflight
(PHYSorg.com Physics)

Hall thrusters (HTs) are used in earth-orbiting satellites, and also show promise to propel robotic spacecraft long distances, such as from Earth to Mars. The propellant in a HT, usually xenon, is accelerated by an electric field which strips electrons from neutral xenon atoms, creating a plasma. Plasma ejected from the exhaust end of the thruster can deliver great speeds, typically around 70,000 mph.