Graduate Thesis Or Dissertation
Modeling, Theoretical and Observational Studies of the Lunar Photoelectron Sheath Public Deposited
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https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/0z708w42x
- Abstract
- The Moon, lacking an atmosphere and a global magnetic field, is directly exposed to both solar ultraviolet radiation and a variety of ambient plasmas. On the lunar dayside, a photoelectron sheath develops and the surface typically charges positively since the photoemission current is at least an order-of-magnitude greater than any ambient current. This sheath dominates the near-surface plasma environment and controls the charging, levitation and transport of micron-sized dust grains. In this thesis, we first model the lunar near-surface plasma environment via a one-dimensional particle-in-cell code. The sheath potential, electric field and plasma densities are presented over a wide range of plasma parameters. Additionally, the charging and transport of micron- and sub-micron sized dust grains is modeled via a test-particle approach in an attempt to explain Apollo-era observations of lunar dust dynamics. Secondly, we present a comparison of the particle-in-cell results with theoretical, kinetic derivations of the lunar photoelectron sheath. We extend previous theories to include the presence of a κ-distribution for the solar wind electrons. Finally, we present a comparison of in-situ measurements of the lunar photoelectron sheet in the terrestrial plasma sheet by the Lunar Prospector Electron Reflectometer with particle-in-cell simulations to confirm the presence of non-monotonic sheath potentials above the Moon. Future work in all three sections, (simulation, theory and observation) is presented as a guide for continuing research.
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- Date Issued
- 2011
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- Last Modified
- 2019-11-16
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Thumbnail | Title | Date Uploaded | Visibility | Actions |
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modelingTheoreticalAndObservationalStudiesOfTheLunarPhot.pdf | 2019-11-11 | Public | Download |