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Title: Landau damping in space plasmas

Abstract

Space plasmas typically possess a particle distribution function with an enhanced high-energy tail that is well modeled by a generalized Lorentzian (or kappa) distribution with spectral index {kappa}. The modified plasma dispersion function {bold Z}{sup *}{sub {kappa}}({xi}) is employed to analyze the Landau damping of (electrostatic) Langmuir waves and ion-acoustic waves in a hot, isotropic, unmagnetized, generalized Lorentzian plasma, and the solutions are compared with the classical results for a Maxwellian plasma. Numerical solutions for the real and imaginary parts of the wave frequency {omega}{sub 0}{minus}{ital i}{gamma} are obtained as a function of the normalized wave number {ital k}{lambda}{sub D}, where {lambda}{sub D} is the electron Debye length. For both particle distributions the electrostatic modes are strongly damped, {gamma}/{omega}{sub 0}{much gt}1, at short wavelengths, {ital k}{lambda}{sub D}{much gt}1. This collisionless damping becomes less severe at long wavelengths, {ital k}{lambda}{sub D}{much lt}1, but the attenuation of Langmuir waves is much stronger for a generalized Lorentzian plasma than for a Maxwellian plasma. This will further localize Langmuir waves to frequencies just above the electron plasma frequency in plasmas with a substantial high-energy tail. Landau damping of ion-acoustic waves is only slightly affected by the presence of a high-energy tail, but is stronglymore » dependent on the ion temperature. Owing to the simple analytical form of the modified plasma dispersion function when {kappa}=2 (corresponding to a pronounced high-energy tail), exact analytical results for the real and imaginary parts of the wave frequency can be found in this case; similar solutions are not available for a Maxwellian plasma.« less

Authors:
 [1];  [2]
  1. Department of Atmospheric Sciences, University of California at Los Angeles, Los Angeles, California 90024-1565 (USA)
  2. Department of Mathematics and Statistics, Memorial University of Newfoundland, St. John's, Newfoundland A1C 5S7 Canada (CA)
Publication Date:
OSTI Identifier:
5666166
Resource Type:
Journal Article
Journal Name:
Physics of Fluids B; (United States)
Additional Journal Information:
Journal Volume: 3:8; Journal ID: ISSN 0899-8221
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; HOT PLASMA; PLASMA WAVES; DISPERSION RELATIONS; DISTRIBUTION FUNCTIONS; ION ACOUSTIC WAVES; ISOTROPY; LANDAU DAMPING; LORENTZ GAS; MODIFICATIONS; SPACE; DAMPING; FLUIDS; FULLY IONIZED GASES; FUNCTIONS; GASES; ION WAVES; IONIZED GASES; PLASMA; 640201* - Atmospheric Physics- Auroral, Ionospheric, & Magetospheric Phenomena

Citation Formats

Thorne, R M, and Summers, D. Landau damping in space plasmas. United States: N. p., 1991. Web. doi:10.1063/1.859624.
Thorne, R M, & Summers, D. Landau damping in space plasmas. United States. doi:10.1063/1.859624.
Thorne, R M, and Summers, D. Thu . "Landau damping in space plasmas". United States. doi:10.1063/1.859624.
@article{osti_5666166,
title = {Landau damping in space plasmas},
author = {Thorne, R M and Summers, D},
abstractNote = {Space plasmas typically possess a particle distribution function with an enhanced high-energy tail that is well modeled by a generalized Lorentzian (or kappa) distribution with spectral index {kappa}. The modified plasma dispersion function {bold Z}{sup *}{sub {kappa}}({xi}) is employed to analyze the Landau damping of (electrostatic) Langmuir waves and ion-acoustic waves in a hot, isotropic, unmagnetized, generalized Lorentzian plasma, and the solutions are compared with the classical results for a Maxwellian plasma. Numerical solutions for the real and imaginary parts of the wave frequency {omega}{sub 0}{minus}{ital i}{gamma} are obtained as a function of the normalized wave number {ital k}{lambda}{sub D}, where {lambda}{sub D} is the electron Debye length. For both particle distributions the electrostatic modes are strongly damped, {gamma}/{omega}{sub 0}{much gt}1, at short wavelengths, {ital k}{lambda}{sub D}{much gt}1. This collisionless damping becomes less severe at long wavelengths, {ital k}{lambda}{sub D}{much lt}1, but the attenuation of Langmuir waves is much stronger for a generalized Lorentzian plasma than for a Maxwellian plasma. This will further localize Langmuir waves to frequencies just above the electron plasma frequency in plasmas with a substantial high-energy tail. Landau damping of ion-acoustic waves is only slightly affected by the presence of a high-energy tail, but is strongly dependent on the ion temperature. Owing to the simple analytical form of the modified plasma dispersion function when {kappa}=2 (corresponding to a pronounced high-energy tail), exact analytical results for the real and imaginary parts of the wave frequency can be found in this case; similar solutions are not available for a Maxwellian plasma.},
doi = {10.1063/1.859624},
journal = {Physics of Fluids B; (United States)},
issn = {0899-8221},
number = ,
volume = 3:8,
place = {United States},
year = {1991},
month = {8}
}