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Degenerate mixing of plasma waves on cold, magnetized single-species plasmas

Anderson, M. W. and O'Neil, T. M. and Dubin, D. H. E. and Gould, R. W. (2011) Degenerate mixing of plasma waves on cold, magnetized single-species plasmas. Physics of Plasmas, 18 (10). Art. No. 102113. ISSN 1070-664X.

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In the cold-fluid dispersion relation ω = ω_p/[1+(k_⊥/k_z)^(2]1/2) for Trivelpiece-Gould waves on an infinitely long magnetized plasma cylinder, the transverse and axial wavenumbers appear only in the combination k_⊥/k_z. As a result, for any frequency ω<ω_p, there are infinitely many degenerate waves, all having the same value of k_⊥/k_z. On a cold finite-length plasma column, these degenerate waves reflect into one another at the ends; thus, each standing-wave normal mode of the bounded plasma is a mixture of many degenerate waves, not a single standing wave as is often assumed. A striking feature of the many-wave modes is that the short-wavelength waves often add constructively along resonance cones given by dz/dr = ±(ω_p^2/ω^2-1)^(1/2). Also, the presence of short wavelengths in the admixture for a predominantly long-wavelength mode enhances the viscous damping beyond what the single-wave approximation would predict. Here, numerical solutions are obtained for modes of a cylindrical plasma column with rounded ends. Exploiting the fact that the modes of a spheroidal plasma are known analytically (the Dubin modes), a perturbation analysis is used to investigate the mixing of low-order, nearly degenerate Dubin modes caused by small deformations of a plasma spheroid.

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Additional Information:© 2011 American Institute of Physics. Received 3 June 2011; accepted 12 September 2011; published online 24 October 2011. The authors wish to thank Matthew Affolter, Francois Anderegg, Fred Driscoll, and Ross Spencer for many useful discussions. This research was supported by grants from NSF (No. PHY-0903877) and DOE (No. DE-SC0002451).
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Department of Energy (DOE)DE-SC0002451
Subject Keywords:damping, dispersion relations, mixing, numerical analysis, perturbation techniques, plasma instability, plasma magnetohydrodynamic waves, viscosity
Issue or Number:10
Classification Code:PACS: 52.35.Bj; 52.35.Qz
Record Number:CaltechAUTHORS:20111221-134324531
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Official Citation:Degenerate mixing of plasma waves on cold, magnetized single-species plasmas M. W. Anderson, T. M. O’Neil, D. H. E. Dubin, and R. W. Gould Phys. Plasmas 18, 102113 (2011); doi:10.1063/1.3646922 (19 pages) Online Publication Date: 24 October 2011
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:28552
Deposited By: Ruth Sustaita
Deposited On:22 Dec 2011 16:50
Last Modified:03 Oct 2019 03:33

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