A simulation of an ion drive in operation

How an ion engine works. Electrons attracted into the discharge chamber collide with xenon atoms from the propellant gas supply, making charged atoms (ions). Current-carrying coils, inside and outside the doughnut-shaped discharge chamber, sustain a magnetic field oriented like the spokes of a wheel. By the Hall effect, ions and electrons swerving in opposite directions in the magnetic field create an electric field. This expels the xenon ions in a propulsive jet. Other emitted electrons then neutralise the xenon, producing the blue jet.
SMART-1 is the first of ESA’s Small Missions for Advanced Research in Technology. It will head for the Moon using solar-electric propulsion and carrying a battery of miniaturised instruments.