Electron Cross-Field Transport in a Miniaturized Cylindrical Hall Thruster

Abstract

Conventional annular Hall thrusters become inefficient when scaled to low power. Cylindrical Hall thrusters, which have lower surface-to-volume ratio, are more promising for scaling down. They presently exhibit performance comparable with conventional annular Hall thrusters. The present paper gives a review of the experimental and numerical investigations of electron crossfield transport in the 2.6 cm miniaturized cylindrical Hall thruster (100 W power level). We show that, in order to explain the discharge current observed for the typical operating conditions, the electron anomalous collision frequency ν B has to be on the order of the Bohm value, ν B ≈ω c /16. The contribution of electron-wall collisions to cross-field transport is found to be insignificant. The optimal regimes of thruster operation at low background pressure (below 10-5 Torr) in the vacuum tank appear to be different from those at higher pressure (~10-4 Torr).

Operation and Plume Measurements of Miniaturized Cylindrical Hall Thrusters with Permanent Magnets

“…1,4 For the miniaturized 100-200 W-class CHTs, the optimal magnetic field configuration was shown to be an enhanced mirror-type (the so-called direct configuration). 6 The highest thruster performance parameters were achieved when the maximum magnetic field at the mirror was ~ 1-1.5 kGauss. 7 In these regimes, the electromagnet coils consumed 50-100 W. For the low power thruster, this additional power consumption reduces drastically the overall thruster efficiency.…”

Effects of Cathode Electron Emission of Hall Thruster Discharge

“…15 Comprehensive studies of the CHT with cusp-type and mirror-type magnetic field configurations are reported elsewhere. 12,15,16 For the miniaturized low power CHT, the optimal magnetic field configuration was shown to be an enhanced mirror-t 17 ype.…”

The effect of alternative propellants on the electron drift instability in Hall-effect thrusters: Insight from 2D particle-in-cell simulations

“…However, evidence suggests that electronwall collisions and secondary electron emissions (SEEs) are not sufficient to explain the observed cross-field electron transport. [25][26][27][28][29][30] Anomalous electron transport may be due to the presence of short-wavelength instabilities in the azimuthal direction, as highlighted by both experimental and numerical studies. [31][32][33][34] Indeed, the large electron drift velocity in the azimuthal direction acts as a driving force for these instabilities [35][36][37] , which result in large amplitude fluctuations in both the plasma density and the azimuthal electric field.…”