자료유형  

 학위논문

Control Number  

0017164505

International Standard Book Number  

9798384044758

Dewey Decimal Classification Number  

530

Main Entry-Personal Name  

Byrne, Matthew P.

Publication, Distribution, etc. (Imprint  

[S.l.] : University of Michigan., 2024

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2024

Physical Description  

205 p.

General Note  

Source: Dissertations Abstracts International, Volume: 86-03, Section: B.

General Note  

Advisor: Jorns, Benjamin A.

Dissertation Note  

Thesis (Ph.D.)--University of Michigan, 2024.

Summary, Etc.  

요약Hall thrusters have become the most popular and successful forms of in-space propulsion ever flown. This is in large part due to their high specific impulse, which enables an increasingly wider mission space. A new push to higher-power and longer-duration missions will expose a unique risk to the spacecraft stemming from the higher exhaust velocities of electric propulsion (EP) thruster plumes. The high-energy ions from the exhaust plume can bombard surfaces of the spacecraft causing erosion. This has a potential to cause problems for the future of EP, as even surfaces exposed to low ion flux can be damaged over the long periods of time expected on an EP powered mission. There is then a pressing and growing need in the EP community to predict the extent of the erosion and, if necessary, devise methods or techniques to potentially mitigate its impact. To meet these growing needs of the community, we performed three studies to address these concerns.In the first study, an investigation into the erosion of a reflector mesh material in the plume of a Hall-effect thruster was presented. Representative samples of the meshed reflector material were exposed to different regions of the thruster plume, and erosion due to ion bombardment is characterized. These results were compared to predictions of an erosion model for non-planar composite materials calibrated to the local plasma parameters and further underscored the need for ways to reduce uncertainty in erosion predictions, or barring that, ways to mitigate it entirely.In the second study, two ion-impact erosion mitigation techniques were demonstrated and validated for sample coupons of spacecraft reflector mesh exposed to the plume of a Hall-effect thruster. In addition, a parametric pressure study was performed to demonstrate the extensibility of the most promising mitigation method to orbital pressure conditions. Profilometry measurements of the post-exposure wire geometries show that both methods significantly decrease the erosion of test coupons of the spacecraft reflector mesh when compared to unexposed control samples. Predictions of wire erosion using plume parameters extrapolated to orbital conditions show a large reduction in erosion for a sample exposed for 10,000 hours. Although these results show great promise for the future use of these techniques, the predictions still rely on valid extrapolations of orbital performance from ground-based data.In the third and final study, changes in the acceleration region dynamics and cathode coupling of a magnetically shielded Hall thruster were characterized under different pressure, electrical, and cathode configurations. A large downstream beam dump was isolated and electrically biased with respect to the ground, while simultaneously the pressure in the facility was varied. The results show that a stable far-field potential can minimally enhance the previously known pressure-related facility effects, and it reinforces that background pressure is a strong driver of how a Hall thruster operates and electrically couples to the facility.Taken together, these studies and the insights gained from them provide a measurable contribution to the current state of knowledge. Further, these results directly address a pressing need in the electric propulsion community, decreasing the risk, and enabling newer and more ambitious missions.

Subject Added Entry-Topical Term  

Physics.

Subject Added Entry-Topical Term  

Aerospace engineering.

Subject Added Entry-Topical Term  

Electrical engineering.

Index Term-Uncontrolled  

Hall thrusters

Index Term-Uncontrolled  

Electric propulsion

Index Term-Uncontrolled  

Spacecraft interactions

Index Term-Uncontrolled  

Orbital pressure conditions

Index Term-Uncontrolled  

Erosion predictions

Added Entry-Corporate Name  

University of Michigan Applied Physics

Host Item Entry  

Dissertations Abstracts International. 86-03B.

Electronic Location and Access  

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Control Number  

joongbu:653993