The ion flux at the exhaust provides the thrust. At the exit plane, the xenon is almost fully ionized.

For these conditions, the current at the anode is several amps. The magnetic strength is such that the electrons tend to be trapped along the magnetic field lines, but the ion trajectories are not significantly influenced by the magnetic field. A magnetic field is applied which is mainly in the radial direction. Gas, typically xenon, flows in from around the anode and is ionized by the electrons which are emitted from the cathode. The cathode is an externally powered hollow cathode or a hot filament positioned slightly past the exit of the dielectric cylinder. A voltage on the order of several more » 100`s of V is applied at the anode (at one end of the cylinder).

The geometry of the SPT is shown it consists of a hollow, cylindrical dielectric (typically of several centimeters length and diameter) with a central dielectric rod. These properties make the SPT of interest for applications such as satellite station-keeping or orbit transfer. For example, arc discharge became very difficult due to the micro-osmotic water (pressure from 3.9 x 10, and a lifetime of several 1000 hours or more. Several special phenomena were observed in examining the characteristics of Freeman Source for a 280 keV ion implanter.

Orbitron r