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Upper-Hybrid Resonance Absorption, Emission, and Heating of an Afterglow Plasma Column

Stenzel, R. L. and Gould, R. W. (1971) Upper-Hybrid Resonance Absorption, Emission, and Heating of an Afterglow Plasma Column. Journal of Applied Physics, 42 (11). pp. 4225-4235. ISSN 0021-8979. doi:10.1063/1.1659758.

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Microwave absorption and emission and electron temperatures of a nonuniform axially magnetized afterglow plasma column in a waveguide geometry have been investigated experimentally. Frequency omega and magnetic field omegac are chosen to satisfy the upper-hybrid resonance condition omega2=omega<sub>c</sub><sup>2</sup>+omega<sub>p</sub><sup>2</sup>(r), where omegap(r) is the local electron plasma frequency. Nearly perfect absorption is observed in the range of upper-hybrid frequencies, while at other frequencies the absorption coefficient is essentially zero. The sharp absorption onset at the maximum upper-hybrid frequency yields an accurate measure for the peak electron density. Density decay and profile in the plasma column are observed—the latter using a new technique. In the range of high absorption the noise emission approaches the blackbody limit. The electron temperature is measured with a radiometer and a reference noise source in a new technique yielding both spatial and time dependence without perturbing the plasma. The time resolution is obtained by a sampling technique. The spatial resolution results from the fact that upper-hybrid resonance absorption and emission are confined to a narrow resonant layer. This property is also used to heat the electrons locally and observe the thermalization process.

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Additional Information:© 1971 The American Institute of Physics. Received 22 March 1971. The authors gratefully acknowledge support from the U.S. Atomic Energy Commission for this work, and various interesting discussions with R.H. Ault concerning the theoretical investigation of the absorption coefficient, and for the use of his numerical results prior to publication.
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Atomic Energy CommissionUNSPECIFIED
Issue or Number:11
Record Number:CaltechAUTHORS:STEjap71
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11600
Deposited By: Archive Administrator
Deposited On:09 Sep 2008 07:02
Last Modified:19 May 2023 16:31

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