Study on the generation and acceleration characteristics of multivalent ions in Hall thruster with large height-radius ratio

The enhancement of multiple ionization is one of the important features of Hall thrusters with large height-radius ratios, and it is crucial to fully comprehend the multiple ionization characteristics and derived effects through effective methods. In this study, an ionization statistical analysis method was developed based on the PIC numerical simulation model, thereby achieving a quantitative decoupling analysis of ionization and acceleration processes. The generation and acceleration characteristics of multivalent ions was investigated based on this. The results demonstrate a significant enhancement in the multiple ionization process of HEP-1350PM characterized by a large height-radius ratio. Compared to SPT-100, the total ionization rate of multivalent ions can be increased by 3.2 %, while the ion acceleration potential can be boosted by 11 %. This enhancement effectively facilitates the improvement of specific impulse of the thruster. For a single discharge process, the higher the valence state of ion, the lower the ion density, the shorter the acceleration interval, the lower the acceleration voltage, and the weaker the erosion of the channel wall. The experimental results validate that despite the lower voltage utilization efficiency of multivalent ions, their energy exhibits a significant increase. The proportion of multivalent ions in the HEP-1350PM plume can be increased by 1.34 % compared to SPT-100, thereby constituting one of the pivotal mechanisms for enhancing its performance. Meanwhile, the contribution of multivalent ions to wall erosion will escalate in tandem with their increasing generation. This study not only elucidates the ionization characteristics and acceleration characteristics of multivalent ions in the Hall thruster with large height-radius ratio but also demonstrates that the ionization statistical analysis method can serve as an effective research tool for quantitatively characterizing discharge characteristics. This study offers theoretical guidance and technical support for further optimization of Hall thrusters with large height-radius ratio.