Operation and Plume Measurements of Miniaturized Cylindrical Hall Thrusters with Permanent Magnets

*§ ** § Two permanent magnet versions of the miniaturized cylindrical Hall thruster (CHT) with different channel outer diameters, 1.5 cm and 2.6 cm, were operated in the power range of 50W-300 W. With twice smaller total power consumption, the 2.6 cm CHT is twice lighter than its electromagnet counterpart. Results of the discharge and plasma plume measurements suggest that the CHT with permanent magnets and electromagnet coils operate rather differently. In particular, the plasma flow from the permanent magnet thrusters has an unusual halo shape of the angular ion current density distribution with a majority of high energy ions flowing at the angles of 50°-70° with respect to the thruster centerline. This divergence of the energetic ion flow leads to the reduced efficiency of the thrust production in these thrusters.