Masters Theses

Abstract

"Surface properties of Hall-effect thruster channel walls play an important role in the performance and lifetime of the device. Physical models of near-wall effects are beginning to be incorporated into thruster simulations, and these models must account for evolution of channel surface properties due to thruster operation. Results from this study show differences in boron nitride channel surface properties from beginning-of-life and after 100's of hours of operation. Two worn thruster channels of different boron nitride grades are compared with their corresponding pristine and shadow-shielded samples. Pristine HP grade boron nitride surface roughness is 9000±700 Å, while the worn sample is 110,900±8900 Å at the exit plane. Pristine M26 grade boron nitride surface roughness is 18400±1400 Å, while the worn sample is 52300±4200 Å at the exit plane. Comparison of pristine and worn channel surfaces also show surface properties are dependent on axial position within the channel. For example, surface roughness increases by as much as a factor of 5.4 and surface atom fraction of carbon and metallic atoms decreases by a factor of 2.9 from anode to exit plane. Macroscopic striations at the exit plane are found to be related to the electron gyroradius and give rise to anisotropic surface roughness. Smoothing of ceramic grains at the microscopic level is also found"--Abstract, page iii.

Advisor(s)

Rovey, Joshua L.

Committee Member(s)

Riggins, David W.
Isaac, Kakkattukuzhy M.
Hilmas, Greg

Department(s)

Mechanical and Aerospace Engineering

Degree Name

M.S. in Aerospace Engineering

Sponsor(s)

Missouri Space Grant Consortium
Missouri University of Science and Technology. Materials Research Center

Publisher

Missouri University of Science and Technology

Publication Date

2011

Pagination

ix, 54 pages

Note about bibliography

Includes bibliographical references (pages 29-32).

Rights

© 2011 David George Zidar, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Subject Headings

Space vehicles -- Electric propulsion systemsBoron nitrideHall effect devicesRocket engines -- Thrust

Thesis Number

T 10226

Print OCLC #

862745024

Electronic OCLC #

732869305

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