Plasma plume of annular and cylindrical hall thrusters

Hall thrusters hold considerable advantage over chemical thrusters and other kinds of electrical propulsion devices, except that the plume of the Hall thruster tends to be wide. An ongoing objective in Hall-thruster research is to narrow this plume. The plume is sensitive both to the specific geometry of the magnetic field as well as to the voltage potential induced within the plasma. Annular-geometry Hall thrusters tend to have narrower plumes. However, the cylindrical-geometry thruster has been shown to be suited particularly to low-power operation. New techniques have been advanced to narrow the Hall-thruster plumes. In this paper, images of the plasma plume in the two geometries of the Hall thruster are presented.