High-Voltage Discharge Optimization of a Hybrid-Wall Hall Thruster

Abstract

A segmented discharge channel is generally adopted in a hybrid-wall Hall thruster. A metallic wall is situated in the upstream portion of the channel, while a boron nitride ceramic wall is retained in the downstream portion of the channel. This hybrid-wall design avoids the disadvantages of the mechanical properties of boron nitride ceramic. Moreover, the channel can be widened by reducing the thickness of the metallic wall upstream of the channel. In this study, the width and configuration of a discharge channel based on a hybrid-wall Hall thruster are investigated, and a convergent channel configuration is adopted. The experimental results show that the configuration of the channel significantly affects the discharge process, and the ionization and acceleration efficiency of the HEP-100HW are substantially improved using the convergent hybrid channel. The specific impulse and efficiency of the HEP-100HW with the optimal convergent hybrid channel are 210 s/2.5% and 270 s/6% higher than those of the HEP-100HW with a straight hybrid channel and the HEP-100 with a straight-configuration ceramic channel at the discharge voltage of 900 V, respectively. Furthermore, from experiments and supporting simulations, it was found that the convergent hybrid-wall design resulted in an increase in the number of ions created further upstream in the channel compared to a conventional design. This led to more efficient acceleration and ejection of the ions out of the channel, resulting in the observed performance improvement. The results from this study provide valuable guidance for the design of high-power and high-voltage Hall thrusters.