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Title: Modeling electronegative plasma discharge

Abstract

Macroscopic analytic models for a three-component electronegative gas discharge are developed. Assuming the negative ions to be in Boltzmann equilibrium, a positive ion ambipolar diffusion equation is derived. The discharge consists of an electronegative core and electropositive edges. The electron density in the core is nearly uniform, allowing a parabolic approximation to the plasma profile to be employed. The resulting equilibrium equations are solved analytically and matched to a constant mobility transport model of an electropositive edge plasma. The solutions are compared to a simulation of a parallel-plane r.f. driven oxygen plasma for p = 50 mTorr and n{sub eo}= 2.4 x 10{sup 15} m{sup -3}. The ratio {alpha}{sub o} of central negative ion density to electron density, and the electron temperature T{sub e}, found in the simulation, are in reasonable agreement with the values calculated from the model. The model is extended to: (1) low pressures, where a variable mobility model is used in the electropositive edge region; and (2) high {alpha}{sub o} in which the edge region disappears. The inclusion of a second positive ion species, which can be very important in describing electronegative discharges used for materials processing, is a possible extension of the model.

Authors:
;  [1]
  1. Univ. of California, Berkley, CA (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
OSTI Identifier:
175504
Report Number(s):
CONF-9505200-
Journal ID: ISSN 0021--8979; ON: DE96000983; TRN: 96:003538
Resource Type:
Conference
Resource Relation:
Journal Volume: 75; Journal Issue: 5; Conference: 13. symposium on energy engineering sciences, Argonne, IL (United States), 15-17 May 1995; Other Information: PBD: [1995]; Related Information: Is Part Of Thirteenth symposium on energy engineering sciences: Proceedings. Fluid/thermal processes, systems analysis and control; PB: 275 p.
Country of Publication:
United States
Language:
English
Subject:
66 PHYSICS; PLASMA; ELECTRONEGATIVITY; MATHEMATICAL MODELS; ELECTRIC DISCHARGES; ELECTRON DENSITY; ELECTRON TEMPERATURE

Citation Formats

Lichtenberg, A J, and Lieberman, M A. Modeling electronegative plasma discharge. United States: N. p., 1995. Web. doi:10.1063/1.356252.
Lichtenberg, A J, & Lieberman, M A. Modeling electronegative plasma discharge. United States. https://doi.org/10.1063/1.356252
Lichtenberg, A J, and Lieberman, M A. 1995. "Modeling electronegative plasma discharge". United States. https://doi.org/10.1063/1.356252. https://www.osti.gov/servlets/purl/175504.
@article{osti_175504,
title = {Modeling electronegative plasma discharge},
author = {Lichtenberg, A J and Lieberman, M A},
abstractNote = {Macroscopic analytic models for a three-component electronegative gas discharge are developed. Assuming the negative ions to be in Boltzmann equilibrium, a positive ion ambipolar diffusion equation is derived. The discharge consists of an electronegative core and electropositive edges. The electron density in the core is nearly uniform, allowing a parabolic approximation to the plasma profile to be employed. The resulting equilibrium equations are solved analytically and matched to a constant mobility transport model of an electropositive edge plasma. The solutions are compared to a simulation of a parallel-plane r.f. driven oxygen plasma for p = 50 mTorr and n{sub eo}= 2.4 x 10{sup 15} m{sup -3}. The ratio {alpha}{sub o} of central negative ion density to electron density, and the electron temperature T{sub e}, found in the simulation, are in reasonable agreement with the values calculated from the model. The model is extended to: (1) low pressures, where a variable mobility model is used in the electropositive edge region; and (2) high {alpha}{sub o} in which the edge region disappears. The inclusion of a second positive ion species, which can be very important in describing electronegative discharges used for materials processing, is a possible extension of the model.},
doi = {10.1063/1.356252},
url = {https://www.osti.gov/biblio/175504}, journal = {},
issn = {0021--8979},
number = 5,
volume = 75,
place = {United States},
year = {Sun Dec 31 00:00:00 EST 1995},
month = {Sun Dec 31 00:00:00 EST 1995}
}

Conference:
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