Study on the Effects of Magnetic Null Point Position on Discharge Structure and Performance in a Double‐Stage Hall Thruster

ABSTRACT The magnetic configuration critically influences the plasma structure and discharge performance of Hall thrusters. However, the effect of magnetic null points on the performance of double‐stage Hall thrusters has not been systematically investigated. In this study, we numerically examine how the spatial location of the second magnetic null point near the channel exit affects plasma behavior and propulsion performance, both in the axial and radial directions. A 2D‐3V PIC/MCC model is developed to simulate the discharge process under different magnetic configurations. The results show that magnetic null point location significantly influences magnetic topology, potential distribution, and the spatial coupling between the ionization and acceleration regions. Optimal thrust and efficiency are achieved when the magnetic null point is axially aligned with the intermediate electrode and radially positioned near the channel wall, forming asymmetric magnetic fields that promote electron energization and localized ionization. In contrast, a centrally located magnetic null point increases magnetic resistance near the walls, disrupts the dual‐region structure, and causes inefficient energy deposition of the electrons. These findings provide new physical insight into magnetic topology control and offer guidance for optimizing field configurations in future double‐stage Hall thruster designs to improve energy utilization and propulsion efficiency.