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Title: Mitigation of electron attachment to oxygen in high pressure air plasmas by vibrational excitation

Abstract

A series of time resolved microwave attenuation measurements are performed of the electron number density of an electron beam generated, CO laser excited nonequilibrium O{sub 2}/N{sub 2} plasma. Resonant absorption of infrared radiation from the CO laser produces the nonequilibrium state, in which the heavy species vibrational modes are disproportionately excited, compared to the rotational and translational modes (T{sub vib}{approx_equal}2000-3000 K vs T{sub R} at {sub {approx}}{sub sol{approx}} at {sub T}{approx_equal}300 K). It is shown that this results in an increase in the plasma free electron lifetime by two orders of magnitude compared to the unexcited cold gas, an effect which is ascribed to complete mitigation of rapid three-body electron attachment to molecular oxygen. A series of heavy species filtered pure rotational Raman scattering measurements are also presented, which exhibit minimal temperature change (+50 K), indicating that the observed lifetime increase cannot be due to heavy-species thermal effects. Finally, computational modeling results infer an increase in the rate of O{sub 2}{sup -} detachment by four to five orders of magnitude, compared to the equilibrium value.

Authors:
; ; ; ; ;  [1];  [2]
  1. Department of Chemistry, The Ohio State University, 650 Ackerman Road, Columbus, Ohio 43202 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20982842
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 9; Other Information: DOI: 10.1063/1.2724796; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BEAM-PLASMA SYSTEMS; CARBON MONOXIDE; ELECTRON ATTACHMENT; ELECTRON BEAMS; ELECTRON TEMPERATURE; EXCITATION; INFRARED RADIATION; MICROWAVE RADIATION; NITROGEN; OXYGEN; PLASMA; PLASMA DENSITY; PLASMA DIAGNOSTICS; PRESSURE DEPENDENCE; RAMAN EFFECT; SIMULATION; TEMPERATURE DEPENDENCE; THREE-BODY PROBLEM; TIME RESOLUTION; VIBRATIONAL STATES

Citation Formats

Frederickson, K., Lee, W., Palm, P., Adamovich, I. V., Rich, J. W., Lempert, W. R., and Department of Mechanical Engineering, The Ohio State University, 650 Ackerman Road, Columbus, Ohio 43202. Mitigation of electron attachment to oxygen in high pressure air plasmas by vibrational excitation. United States: N. p., 2007. Web. doi:10.1063/1.2724796.
Frederickson, K., Lee, W., Palm, P., Adamovich, I. V., Rich, J. W., Lempert, W. R., & Department of Mechanical Engineering, The Ohio State University, 650 Ackerman Road, Columbus, Ohio 43202. Mitigation of electron attachment to oxygen in high pressure air plasmas by vibrational excitation. United States. doi:10.1063/1.2724796.
Frederickson, K., Lee, W., Palm, P., Adamovich, I. V., Rich, J. W., Lempert, W. R., and Department of Mechanical Engineering, The Ohio State University, 650 Ackerman Road, Columbus, Ohio 43202. Tue . "Mitigation of electron attachment to oxygen in high pressure air plasmas by vibrational excitation". United States. doi:10.1063/1.2724796.
@article{osti_20982842,
title = {Mitigation of electron attachment to oxygen in high pressure air plasmas by vibrational excitation},
author = {Frederickson, K. and Lee, W. and Palm, P. and Adamovich, I. V. and Rich, J. W. and Lempert, W. R. and Department of Mechanical Engineering, The Ohio State University, 650 Ackerman Road, Columbus, Ohio 43202},
abstractNote = {A series of time resolved microwave attenuation measurements are performed of the electron number density of an electron beam generated, CO laser excited nonequilibrium O{sub 2}/N{sub 2} plasma. Resonant absorption of infrared radiation from the CO laser produces the nonequilibrium state, in which the heavy species vibrational modes are disproportionately excited, compared to the rotational and translational modes (T{sub vib}{approx_equal}2000-3000 K vs T{sub R} at {sub {approx}}{sub sol{approx}} at {sub T}{approx_equal}300 K). It is shown that this results in an increase in the plasma free electron lifetime by two orders of magnitude compared to the unexcited cold gas, an effect which is ascribed to complete mitigation of rapid three-body electron attachment to molecular oxygen. A series of heavy species filtered pure rotational Raman scattering measurements are also presented, which exhibit minimal temperature change (+50 K), indicating that the observed lifetime increase cannot be due to heavy-species thermal effects. Finally, computational modeling results infer an increase in the rate of O{sub 2}{sup -} detachment by four to five orders of magnitude, compared to the equilibrium value.},
doi = {10.1063/1.2724796},
journal = {Journal of Applied Physics},
number = 9,
volume = 101,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}