Discharge characteristics of a Kilowatt Hall effect thruster with a variable channel

A kilowatt-order Hall effect thruster with a variable channel, the HET72-VC, is proposed. The discharge channel consists of an inner divergent annular segment and a cylindrical segment near the exit. A discharge comparison experiment was conducted on this thruster, in which the propellant gas is supplied along the axial direction and along the channel centerline. The results show that under the condition of gas supply along the channel centerline, both the current utilization and propellant utilization are higher, the plume divergence angle is smaller, the ion energy distribution curve moves to the high-energy portion, and the overall discharge performance, including the thrust and anode efficiency, is improved. A theoretical analysis shows that these results are attributed to the change in the ionization and acceleration characteristics caused by the different gas supply directions. The HET72-VC is demonstrated to be able to operate stably at an electric power of 2.5 kW; compared with those Hall effect thrusters with the same outer diameter or flow area of the channel, its thrust density and power density are both greatly improved. This provides a new perspective for the development of a high-power Hall effect thruster with a compact structure.