A novel approach for pole erosion mitigation in Hall thrusters: Design and mechanism of an internally loaded magnetic field

Permanent magnet Hall thrusters with large height-radius ratio offer significant advantages for lightweight design but suffer from severe magnetic pole erosion due to the divergent magnetic field configuration and compact structure. To address this issue, an internally loaded magnetic field (ILMF) configuration is proposed by employing a segmented magnetic screen and an optimized magnetic circuit, which shifts the strong magnetic field, ionization, and primary potential drop regions toward the interior of the discharge channel while moving the magnetic pole surfaces axially inward. Particle-in-cell (PIC) simulations show that the ILMF-configured Hall thruster reduces the peak ion flux and peak ion energy on the magnetic pole surfaces by 90% and 91%, respectively. In addition, electron flux and energy are reduced, and the ion incidence angle distribution is improved, effectively mitigating magnetic pole erosion. The ILMF-configured Hall thruster also improves magnetic field utilization, increasing the height-radius ratio from 0.67 to 0.81 while reducing the channel outer diameter by 5%. Under the rated operating condition, the thrust and specific impulse increase by 6.3% and 6.1%, respectively, and the total efficiency improves from 54.2% to 60.5%. Although the ion power loss on walls increases by 5.4%, the wall power deposition becomes more uniform. These results demonstrate that the ILMF provides an effective magnetic circuit design for lightweight, high performance, and highly reliable permanent magnet Hall thrusters with large height-radius ratio.