Collisional Damping Of Plasma Waves On A Pure Electron Plasma Column
- Department of Physics, University of California at San Diego, 9500 Gilman Drive, La Jolla, California 92093 (United States)
The collisional damping of electron plasma waves (or, more precisely, Trivelpiece-Gould waves) on a pure electron plasma column is discussed. The damping in a pure electron plasma differs from that in a neutral plasma, since there are no ions to provide collisional drag. A dispersion equation for the complex wave frequency is derived from Poisson's equation and the drift-kinetic equation with the Dougherty collision operator--a Fokker-Planck operator that conserves particle number, momentum, and energy yet is analytically tractable. In the limit of weak collisionality, for phase velocity comparable to the thermal velocity, Landau damping is recovered. For larger phase velocity, where Landau damping is negligible, the dispersion equation can be solved analytically, yielding the complex frequency {omega} (k{sub z}{omega}{sub p}/k)[1+(3/2)(k{lambda}{sub D}){sup 2}(1+10i{alpha}/9)(1+2i{alpha}){sup -1}], where {omega}{sub p} is the plasma frequency, k{sub z} is the axial wavenumber, k is the total wavenumber, {lambda}{sub D} is the Debye length, {nu} is the collision frequency, and {alpha}{identical_to}{nu}k/{omega}{sub p}k{sub z}. This expression spans from the weakly collisional regime ({alpha}<<1)) to the strongly collisional regime ({alpha}>>1), matching onto fluid results in the latter limit. Note that in the weakly collisional regime the damping rate is given by Im({omega}) congruent with -4{nu}(k{lambda}{sub D}){sup 2}/3, which is suppressed from the damping rate in a neutral plasma [Im({omega}) congruent with -{nu}/2] by the factor (k{lambda}{sub D}){sup 2}<<1; this suppression reflects the conservation of electron momentum in the pure electron plasma. In the limit of strong collisionality, the damping is enhanced by cross-field transport resulting from long-range collisions. These collisions are neglected in the kinetic treatment, but their contribution to the damping is estimated from fluid theory.
- OSTI ID:
- 21300430
- Journal Information:
- AIP Conference Proceedings, Vol. 1114, Issue 1; Conference: Non-neutral plasma physics VII: Workshop on non-neutral plasmas 2008, New York, NY (United States), 16-20 Jun 2008; Other Information: DOI: 10.1063/1.3122272; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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