Coupling plasma plume of a low-power magnetically shielded Hall thruster with a hollow cathode

The coupling region of a Hall thruster with a hollow cathode is the region between the cathode and the thruster plume. The characteristics of plasma in that region are complicated and strongly associated with the thruster working conditions and the cathode position. In this paper, a laboratory 100 W class magnetically shielded Hall thruster was coupled with a hollow cathode. Optical imaging and electrostatic probe were employed to monitor and scan the plasma plume. Plume characteristics in the coupling region in non-self-sustained mode and self-sustained mode were compared. Evolution of the coupling plume with the cathode position was studied. Experiments show that, when turning the thruster into self-sustained mode or moving the cathode further away axially, the discharge current can be reduced by 6.4–10.6% restraining the electron current and improving ionization. In particular, when the cathode is moved further, the electron conduction near the channel walls is suppressed. The electron current is reduced by 27.4% and the ion beam current is increased by 7%. Overall, this work shows that the working mode of the thruster and the position of the cathode greatly affect the coupling plasma plume. Both play an important role in improving the utilizations of propellant and current.