Cylindrical Hall Thrusters with Permanent Magnets

Abstract

The use of permanent magnets instead of electromagnet coils for low power Hall thrusters can offer a significant reduction of both the total electric power consumption and the thruster mass.Two permanent magnet versions of the miniaturized cylindrical Hall thruster (CHT) of different overall dimensions were operated in the power range of 50W-300 W. The discharge and plasma plume measurements revealed that the CHT thrusters with permanent magnets and electromagnet coils operate rather differently. In particular, the angular ion current density distribution from the permanent magnet thrusters has an unusual halo shape, with a majority of high energy ions flowing at large angles with respect to the thruster centerline. Differences in the magnetic field topology outside the thruster channel and in the vicinity of the channel exit are likely responsible for the differences in the plume characteristics measured for the CHTs with electromagnets and permanent magnets. It is shown that the presence of the reversing-direction or cusp-type magnetic field configuration inside the thruster channel without a strong axial magnetic field outside the thruster channel does not lead to the halo plasma plume from the CHT.

Cathode Effects on Operation and Plasma Plume of the Permanent Magnet Cylindrical Hall Thruster

“…The defocusing of energetic ions could explain lower efficiencies measured for the CHT with permanent magnets as compared to the electromagnet CHT. 1,6 In recent studies, 2 we demonstrated that the differences in the plume and performance characteristics between the cylindrical thrusters with electromagnet coils and permanent magnets are associated mainly with a stronger axial magnetic field outside the channel of the thruster with permanent magnets. For the permanent magnet thrusters, this outside magnetic field connects naturally to the location of the magnetic separatrix with respect to the thruster channel exit.…”

“…Cylindrical geometry Hall thrusters 3,4 have lower surface-to-volume ratio than conventional annular Hall thrusters and, thus, seem to be more promising for scaling down to operate at low power levels. Two permanent magnet versions of the miniaturized cylindrical Hall thruster (CHT) of different overall dimensions were operated in the power range of 50W-300 W. 1,2,5,6 The discharge and plasma plume measurements revealed that the CHT with permanent magnets (CHTpm) and electromagnet coils (CHTem) operate rather differently. In particular, the angular ion current density distribution from the permanent magnet thrusters has an unusual halo shape, with a majority of high energy ions flowing at large angles with respect to the thruster centerline.…”

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

“…2 compares results of simulations of the magnetic field for the 2.6 cm outer channel diameter CHT thrusters with electromagnets and permanent magnets. 4 The CHT with permanent magnets (CHTpm) uses two axially magnetized permanent magnet rings made from a cobalt-samarium alloy. These magnet rings are incorporated into the thruster magnetic circuit as shown in Fig.…”

“…Two permanent magnet versions of the miniaturized cylindrical Hall thruster (CHT) of different overall dimensions were operated in the power range of 50W-300 W. 3,4 The discharge and plasma plume measurements revealed that the CHT with permanent magnets and electromagnet coils operate rather differently. In particular, the angular ion current density distribution from the permanent magnet thrusters has an unusual halo shape, with a majority of high energy ions flowing at large angles with respect to the thruster centerline.…”

Effect of Orifice Diameter on the Performance of a Miniature Microwave Neutralizer

“…[1][2][3] Ion and Hall thrusters have emerged as two of the most used electric propulsion schemes. 2,[4][5][6] The operation of such propulsion systems require the use of an electron source, referred to as the "neutralizer." [7][8][9][10][11][12] The various limitations imposed upon the geometry, power, and material requirements of the neutralizers for space propulsion make their development challenging.…”