Optimization of a Long-Lifetime Hall Thruster with an Internally Mounted Cathode

Hall thrusters with an internal cathode are widely used due to their ability to enhance efficiency, minimize plume divergence, and eliminate plume asymmetry. In addition, the long-lifetime technology of Hall thrusters typically relocates the intense magnetic-field region outside the channel, known as an "aft-loaded magnetic field," to mitigate erosion of the discharge channel caused by high-energy ions. However, this exacerbates plume divergence and diminishes overall performance. Therefore, this research focuses on optimizing a Hall thruster with an aft-loaded magnetic field and internal cathode. Given that electrons emitted by the internal cathode initially diffuse onto the magnetic separatrix and subsequently couple with the ion beam in the plume, this study experimentally investigates the impact of the magnetic separatrix shape on the discharge characteristics and plume behavior of the Hall thruster. The experimental findings indicate that expanding the envelope of the magnetic separatrix contributes to improved plume focusing and enhanced performance. Thus, the results of this study highlight the significance of the magnetic field outside the channel as a crucial design factor for long-lifetime Hall thrusters.