Investigation of an electron-beam sustained discharge in helium
Schatz, Kenneth David
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https://hdl.handle.net/2142/22977
Description
Title
Investigation of an electron-beam sustained discharge in helium
Author(s)
Schatz, Kenneth David
Issue Date
1995
Doctoral Committee Chair(s)
Ruzic, David N.
Department of Study
Physics, Fluid and Plasma
Discipline
Physics, Fluid and Plasma
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Fluid and Plasma
Language
eng
Abstract
Results of an experimental and theoretical investigation into an Electron-Beam Sustained Discharge (EBSD) confined within an electrically insulating cylindrical discharge tube are presented. The study is directed toward discharges in helium where radial ambipolar diffusion is the dominant plasma loss mechanism. This investigation is made in support of a continuing, technology-driven program to apply the unique attributes of the EBSD to plasma processing applications in the growth and etching of thin films.
Results of an electron-fluid model, including predictions of electron temperature, electric field strength within the discharge, and electron density, are presented for a range of helium densities between 1.0E15 and 1.0E16 #/cm$\sp3$, discharge tube radii from 1.0 to 10.0 cm, electron-beam energy deposition rates in the neighborhood of 1.0E16 eV/sec/cc, and glow discharge currents from 0.0 to 250. mA. Modeling predictions are compared with experimental measurements of an EBSD. A majority of the experimental data presented are for the case of an EBSD in 0.25 Torr helium and a discharge tube of radius 3.65 cm with a beam energy deposition rate of approximately 1.3E16 eV/sec/cc and glow discharge currents between 0.0 and 185 mA. Modeling results are shown to display all of the trends seen in the experimental data, except that of the electron density when the electron temperature is low. It is argued that this effect is due to the over-abundance of high-energy electrons, relative to a Maxwell-Boltzmann distribution, that is inherent in electron-beam-driven plasmas.
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