Dissertation Committee Names:

Professor Alec D. Gallimore, Co-Chair
Assistant Professor Benjamin A. Jorns, Co-Chair
Professor John E. Foster, Cognate
Dr. Richard R. Hofer, Member

Presentation Info:

Thursday, September 26th 2 PM
Johnsons Room, LEC

This work examines two innovative technologies in high-power electric propulsion – magnetic shielding and nesting channels. Magnetic shielding increases the lifetime of Hall thrusters by three orders of magnitude, while nested Hall thrusters allow these devices to be scaled to the very high powers necessary for Mars missions. Despite these advancements, there remain open questions about the exact implications on Hall thruster operation. These open questions pose large risks for transitioning the thrusters to flight. One of the most critical is how neutral gas particles emanating from various sources influence the overall performance and lifetime of these thrusters. There exist several sources of neutrals such as the background facility pressure, the cathode, and adjacent channels on nested Hall thrusters. As such, we investigate here the neutral density impacts on the operation of high-power Hall thrusters. In summary, we show that neutrals shift and compress the plasma, which leads to an increase thrust and efficiency with higher neutral density. Additionally, we find that these neutrals can change the near-wall ion behavior, which affects the erosion and overall lifetime. Ultimately, we have improved our understanding of the mechanisms behind neutral impacts on the performance and lifetime of magnetically shielded and nested Hall thrusters.