Hall-magnetohydrodynamic analysis of acceleration length and magnetic field optimization in an argon Hall thruster

A zero-dimensional Hall-magnetohydrodynamic (Hall-MHD) model is used to examine the influence of magnetic flux density B on the acceleration length La and overall performance, using experimental data obtained during argon operation of the RAIJIN66 Hall thruster. The model is derived from the equivalence between electrostatic ion acceleration and electromagnetic thrust generated by the J × B force. The results show that the acceleration length scales approximately as La∝1/B, consistent with anomalous diffusion theory. Within the investigated range, an increase in acceleration length is associated with improved performance at fixed mass flow rate. A strong dependence on discharge voltage is observed, with operation at 150 V benefiting from reduced magnetic flux density, indicating a MHD-like regime in which an extended acceleration length is advantageous. These findings suggest that the low-voltage regime identified here may be representative of future high-density thruster operation, where reduced magnetic flux density is associated with improved performance.