2D PIC Simulations of Radial Magnetic Field Effects on Electron Drift Instability and Anomalous Axial Transport in Hall Thrusters

The Hall thruster is an electromagnetic plasma accelerator widely used in spacecraft propulsion. In the thruster channel exit region, where the strong E×B field exists, high-frequency electron drift instability (EDI) arises, driving anomalous axial electron transport. While the physical characteristics of EDI have been extensively studied, the impact of radial magnetic field intensity and gradient within the radial–azimuthal configuration remains largely unexplored. In this study, two-dimensional (2D) particle-in-cell (PIC) simulations are conducted on the radial–azimuthal plane at the channel exit. Results indicate that, in the presence of uniform radial magnetic fields, increasing the field strength reduces the electron drift velocity and Larmor radius, thereby enhancing electron confinement in crossed fields. This also decreases the relative azimuthal drift between electrons and ions, leading to weaker electron-ion friction, suppressed ion heating, and inhibited EDI development. Furthermore, radial gradient magnetic fields prove more effective in suppressing axial electron mobility and EDI, shifting the instability spectrum toward longer wavelengths and lower frequencies, further mitigating anomalous transport. These findings suggest that tailored radial magnetic field profiles, particularly with gradients, can effectively suppress electron drift instability and anomalous axial transport, thereby improving Hall thruster discharge performance and stability.