Doctoral Dissertations

Jianxun Zhao

Keywords and Phrases

Lunar dust levitation; Lunar dust transport; Lunar exploration; Lunar surface charging; PIC simulation; Solar wind and solar radiation

Abstract

"The studies involving lunar surface explorations have drawn attentions in recent years. A better understanding of possible potential hazards to astronauts and electronic equipment has become a necessity for future lunar explorations. The lunar surface, lacking an atmosphere and global magnetic field therefore directly exposed to solar radiation and solar wind plasma, is electrically charged by the bombardment of solar wind plasma and emission/collection of photoelectrons. Additionally, lunar dust grains can also get charged and levitated from the surface under the influence of the electric field as well as gravity within the plasma sheath. Since the plasma sheath formed near the illuminated lunar surface is dominated by photoelectrons, it is usually referred to as 'photoelectron sheath'.

In this research, we will focus on resolving the photoelectron sheath structure near lunar surface through numerical simulations. Firstly, we will introduce the fundamental assumptions of our analytic and simulation studies. We will present the derivation of a 1-D semi-analytic model to numerically obtain the quantities of interest as functions of the distance from surface within the photoelectron sheath. Secondly, we will present the numerical simulations with a fully kinetic Finite Difference (FD) Particle-in-Cell (PIC) code to solve the surface charging problem on lunar surface. In this study, we will consider both Maxwellian and Kappa distribution of solar wind electron velocities. Finally, we will show our current studies on the charged lunar dust lofting and transport under the influence of local electrostatic environment. We will consider both uncoupled and coupled method in the simulations. In uncoupled method, a steady state electric field is obtained through FD-PIC simulations and provided to simulate the charged dust transport, indicting that the charged dust transport does not influence the local electrostatic environment. Whereas in the coupled method, the electrostatic environment and the charged dust transport are simulated simultaneousness, which means the electrostatic environment and the dust transport influence each other during the simulations"--Abstract, page iii.

Advisor(s)

Han, Daoru Frank

Committee Member(s)

He, Xiaoming
Hosder, Serhat
Pernicka, Henry J.
Yan, Guirong Grace

Department(s)

Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Aerospace Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2022

Pagination

xvi, 150 pages

Note about bibliography

Includes bibliographic references (pages 144-149).

Rights

© 2022 Jianxun Zhao, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 12169

Electronic OCLC #

1344518777

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