Electronic Theses and Dissertations

Identifier

6400

Date

2019

Date of Award

4-29-2019

Document Type

Thesis

Degree Name

Master of Science

Major

Mechanical Engineering

Concentration

Mechanical Engineering

Committee Chair

Ranganathan Gopalakrishnan

Committee Member

John Hochstein

Committee Member

Mohamed Laradji

Abstract

Determination of the charge on particles within aerosol and dusty plasmas is key to describing the dynamics within them. The large size and mobility difference between ions and electrons results in particles which accumulate negative and positive charge at different rates. Moreover, the particles within these aerosols are typically surrounded by neutral molecules whose density depends on the pressure of the system. These gas molecules play an important role in determining the trajectories of the ions and hence the rate at which they are collected by the grain, referred to as the collision rate H. The value of H obtained from continuum approach breaks down as collisions with gas molecules become rare while a description for H derived from kinetic theory only works when neutral gas molecules are absent. The Langevin Equation is used to simulate ensemble ion trajectories in this transition regime and the collision times are found to be accurately described by the Gumbel distribution. The aforementioned understanding of the collision time distribution is used to infer a model to calculate the collision rate H as a function of the Knudsen number and a non-dimensional parameter representing the electrostatic potential between the ion and particle.

Comments

Data is provided by the student.

Library Comment

dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.

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