Performance Analysis of a Low-Power Magnetically Shielded Hall Thruster: Experiments

Abstract

The successful application of a fully shielding magnetic field topology in a low-power Hall thruster is demonstrated through the testing of the MaSMi-60 Hall thruster (an improved variant of the original Magnetically Shielded Miniature Hall thruster). The device was operated at discharge powers from 160 to 750 W at discharge voltages ranging from 200 to 400 V. Several techniques were used to determine the effectiveness of magnetic shielding achieved by the MaSMi-60 and to estimate the reduction in discharge channel erosion rate enabled by the shielding field topology. This ultimately suggested an improvement in discharge channel life by a factor of at least 10 times, and likely greater than 100 times, when compared to unshielded devices. Thruster performance, measured both directly by a thrust stand and indirectly by plume diagnostics, was lower than expected when compared to results from high-power magnetically shielded Hall thrusters. However, the plume diagnostic measurements enabled the identification of the primary causes for the MaSMi-60's moderate performance.

Operation of a low-power Hall thruster: comparison between magnetically unshielded and shielded configuration

“…The larger MaSMi-60-LM1 was then developed and reached nearly 0.29 anode efficiency around 500 W [19]. This thruster was extensively simulated with Hall2De to understand why such a low efficiency is achieved [20].…”

“…One of the main limitations of low power (< 500 W) Hall thrusters is their lifetime. While thrusters in the 1 to 5 kW range can achieve up to 10 000 hours of operation [2] small HT are usually limited to 3 000 hours [3]. The life limiting factor for HT is the erosion of the discharge channel by fast ions.…”

Distinct discharge modes in micro Hall thruster plasmas

“…These results suggest that the overlapped region between the ionization and the acceleration regions gradually increases with in Mode A, while the extent of overlap saturates in Mode B regardless of , as reported in Refs. [34][35][36]. For the sake of comparison, the IEDF from another group (blue) is also plotted in the figure [35].…”

“…[34][35][36]. For the sake of comparison, the IEDF from another group (blue) is also plotted in the figure [35].…”

“…(b)The full width at half maximum of the ion energy distribution functions for the two modes. For comparison, the IEDF from another group (blue) is also plotted[35].…”