Role of Magnetic Field Steepness in Efficiency of High-specific-impulse Hall Thrusters

Hall thrusters are a type of electric propulsion system known for their simplified structure compared to other systems, such as chemical propulsion and Gridded Ion Engines. This feature makes them a promising candidate for extraterrestrial planetary exploration, where efficiency and reliability are crucial. For missions beyond Jupiter, achieving a specific impulse of 4,000 seconds—a key measure of fuel efficiency—is necessary for transporting exploration equipment over long distances. However, current Hall thrusters using Xenon as a propellant have not yet reached this specific impulse. To address this, we are researching the development of a high-voltage Hall thruster aimed at exceeding 4,000 seconds of specific impulse.

In this presentation, we will explore how the relative positioning of the discharge channel and magnetic field topology significantly affects the performance of a high-voltage Hall thruster. Specifically, we will discuss results from comparative experiments on the sharpness of the Hall thruster’s radial magnetic field (Br) and its impact on discharge behavior, ionization processes, and plume characteristics. Additionally, we will focus on anode efficiency, which reflects how effectively input power is converted into propulsive energy. Based on these findings, we will propose magnetic field design guidelines for optimizing specific impulse, improving overall efficiency, and enabling high-efficiency operation in future Hall thruster designs.