The far-field plasma characteristics of LHT40 low-power Hall thruster for commercial aerospace applications

To achieve a better insight into the far-field plasma spatial distribution and evolution characteristics of the 300 W class low-power Hall thruster (LHT) for commercial aerospace applications, a dedicated and integrated plasma diagnostic system composed of seventeen Faraday cups (FC) and two triple Langmuir probes (TLP) is established to investigate the time-averaged in situ spatial distribution characteristics of far-field ions and electrons. The ion current density (ICD), plasma potential, plasma density, and electron temperature at 1000 mm downstream of 300 W class LHT for commercial aerospace applications in the azimuthal angle range of −90° to 90° were investigated under the conditions of different anode mass flow rates and discharge voltages. The results demonstrated that ICD, beam divergence angle, and mass utilization efficiency increased with increasing anode mass rate. The double-wings phenomenon was observed in the spatial distribution of ICD at large angles from the thruster axis, which is attributed to charge exchange collisions at increasing vacuum backpressure. The plasma electron temperature, electron density, and plasma potential parameters derived from the TLP decreased rapidly in the angle range from 0° to 30° and did not exhibit significant variations above 30°, which was also in good agreement with the results of the measured divergence angle of the FC. The discrepancy of average ion speed was calculated. The maximum error is better than 31.5% which checks the consistency between the TLP's results and that of FC to some extent.