Masters Theses

Keywords and Phrases

Photoemission driven cavities; space-charge limited emission

Abstract

"This work presents a computational experiment simulating irradiation of gold in a cylindrical cavity. The full 3-D simulation with a B-Dot diagnostic is modeled, and a subset of the results are compared to modeling the system as a coupled anode/cathode (AK) gap and transmission line. The cavity is filled with N2 and Ne gasses at pressures ranging from vacuum to 1000 mTorr. Space-charge limited emission physics, electric discharge physics, LC circuit physics, and Monte-Carlo methods are explored.

The computation process happens in two steps. First, the electron emission material is irradiated with an input x-ray photon spectrum to produce a photoelectron emission spectrum. This is accomplished using a Monte-Carlo photon-electron radiation transport code. The photoelectron spectrum, together with the x-ray time pulse and yield, is then used to characterize the electron emission into the gas filled cylindrical cavity that is modeled via an electromagnetic (EM) particle-in-cell (PIC) code. Each surface produces a different photoelectron emission spectrum and drives a current through the experiment that is measured in an output cavity. The effects of plasma dynamics, including plasma formation due to electron impact ionization within the cavity, are studied. Modeling the system as a coupled gas filled cavity and transmission line significantly reduces computational resources and provides accurate results. A transmission line was used to model the circuit of this geometry, and an axial configuration is shown to be a more viable method of modeling this geometry than a radial configuration. Finally, a comparison of different diagnostic geometries (a driven X-ray diode) is discussed"--Abstract, p. iii

Advisor(s)

Alajo, Ayodeji Babatund

Committee Member(s)

Alam, Syed B.
Graham, Joseph T.

Department(s)

Nuclear Engineering and Radiation Science

Degree Name

M.S. in Nuclear Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2024

Pagination

xiv, 93 pages

Note about bibliography

Includes_bibliographical_references_(pages 91-92)

Rights

© 2023 Ravi Sanjay Shastri, All rights reserved

Document Type

Thesis - Open Access

File Type

text

Language

English

Thesis Number

T 12352

Electronic OCLC #

1426307860

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