Effect of wall divergence angle on Hall thruster performance

摘要

A discharge channel with a divergent configuration not only has the application in the design of modern Hall thrusters, but also exists where the thruster channel wall is eroded, and is thus a common status that a Hall thruster has. In order to understand more deeply the interaction between discharge plasma and channel wall and provide references for the design of modern Hall thrusters, the rule and mechanism that a divergent channel affects the performance of a Hall thruster are investigated in this paper. With both the experimental measurement and Particle-in-Cell simulation, it is found that there is a moderate divergence angle that can further improve the optimal performance obtained with a straight channel. The reason is that the divergence of channel near the channel exit can enhance ion acceleration and reduce ion recombination on the wall effectively, which is favorable for the promotion of thrust and efficiency. However, the divergence angle should not be too large; otherwise, both the density of propellant gas and the two dimensional distribution of plasma potential in the channel would be influenced, which is harmful for the propellant utilization and beam concentration. Therefore, the divergence angle of the channel could be an important factor when designing a modern Hall thruster.