Performance and Active Thermal Control of a 2-kW Hall Thruster with Segmented Electrodes

Propellant Thermal Management Effect on Neutral Residence Time in Low-Voltage Hall Thrusters

“…This led to the reverse injection technique used in state of the art gridded ion engines. Kieckhafer et al used a shim anode in the HET, which allows for splitting of the discharge current between the gas distributor and an auxiliary anode [4]. They show that an increase in the shim anode current decreases the anode temperature, which causes an increase in the beam current.…”

Effect of segmented anodes on the performance and plume of a hall thruster

“…15 This thermal control strategy has been successfully implemented in a Hall thruster, and the temperatures achieved by the anode and the shims are plotted in Figure 1-4 for a typical experiment with the thruster. 16 Anode and propellant diffuser One use of segmented electrodes in previous studies was as a method of achieving two-stage operation, 8,9 where the shim electrodes are maintained at a potential between the anode and the cathode, allowing for an acceleration-only stage which would allow the propellant to be accelerated to very high velocities. A diagram of one two-stage thruster design is in Figure 1-5.…”

“…17, , 18 19 These investigations showed that the divergence of the thruster plume could be improved through the use of segmented electrodes, as shown in Figure 1 segmented anodes as a thermal control mechanism showed little change in thruster performance or beam profile. 16,20 Additionally, the experiments showed that while the thruster design used could not achieve the absolute temperatures expected to be necessary for bismuth evaporation, a control authority of nearly 100 C was available on the main anode, allowing for significant throttling capability.…”

Evaluation of Magnesium as a Hall Thruster Propellant

“…Decreasing the potential of the shims and increasing the current attached to the main anode increased the Joule heating, increasing the temperature of the main anode. Adding current to the main anode from the shims could arrest a cold runaway condition.Kieckhafer's experiments were successful in demonstrating the ability to raise and lower the anode temperature of a xenon hall thruster with a control window of 50° C[52].…”

“…The work presented in this chapter describes a method for condensable propellant mass flow control, which needs very little additional heat while maintaining precise control of the mass flow rate. the shim anode approach was unsuccessful for use in direct evaporation Hall thrusters, the experiments associated with development of this technique have demonstrated two important points: (1) the natural plasma discharge heat input to a Hall thruster anode is of sufficient magnitude to evaporate condensable propellants at ratescommensurate with normal operation, and (2) the evaporation rate from the anode can be adjusted by adding or subtracting small amounts of heat to/from the evaporative anode[15,52]. The goal of the work reported in this chapter is to capture the primary benefit of the direct-evaporation scheme, namely to use plasma discharge waste heat to drive the evaporation, but to abandon the shim-anode control technique in favor of a straightforward supplemental resistive heater used to augment the plasma heating.…”