Effect of the Magnetic Field on the Plasma Plume of the Cylindrical Hall Thruster with Permanent Magnets

A low power miniaturized cylindrical Hall thruster with permanent magnets (CHTpm) was operated with and without the magnetic shield. The magnetic field outside the thruster channel is shown to play a critical role in the formation of an unusual halo shape of the plasma flow from CHTpm without the magnetic shield. It is suggested that this result is applicable for other types of permanent magnet cylindrical thrusters, including diverge-cusp field (DCF) and HEMP thrusters. For the CHTpm, the use of a magnetic shield allows to restore a conic shape of the plasma plume, which is typical for conventional annular Hall thrusters and cylindrical Hall thrusters with electromagnets, and to reduce the plasma plume divergence.