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Title: Existence of non-Landau solutions for Langmuir waves

Abstract

The propagation of linear one dimensional (1D) Langmuir waves is reinvestigated using numerical simulations of a new type with very low noise. The dependence of the result on the initial conditions is shown. New solutions are exhibited, with properties different from Landau's, even in the asymptotic behavior, in particular with regard to the damping rate. These solutions are shown to demand a special preparation of the initial plasma perturbation, but in a way which is quite physical, without any singularity in the electron distribution function, contrary to the classical van Kampen's solutions. Using an original theoretical calculation, a simple analytical form is derived for the perturbed distribution function, which allows interpreting both the Landau and non-Landau solutions observed numerically. The numerical results presented and their interpretations are potentially important in several respects: 1) They outline that Landau solutions, for the 1D electrostatic problem in collisionless plasmas, are only a few among an infinite amount of others; even if the non-Landau solutions are much less probable, their existence provides a different view on the concept of kinetic damping and may suggest interpretations different from usual for the subsequent nonlinear effects; 2) they show that the shape of the initial perturbation {delta}f(v),more » and not only its amplitude, is important for the long time wave properties, both linear and nonlinear; 3) the existence of non-Landau solutions makes clear that the classical energy arguments cannot be fully universal as long as they allow deriving the Landau damping rate independently of the initial conditions; 4) the particle signature of Landau damping, different from the usual guess, should imply a change in our understanding of the role of the resonant particles.« less

Authors:
;  [1];  [2];  [2]
  1. Centre d'etude des Environnements Terrestre et Planetaires (CETP), CNRS/UVSQ/UPMC, 10-12 Avenue de l'Europe, 78140 Velizy (France)
  2. Laboratoire Univers et Theories (LUTH), Observatoire de Paris, CNRS, Universite Paris-Diderot, 5 Place Jules Janssen, 92190 Meudon (France)
Publication Date:
OSTI Identifier:
21120304
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 15; Journal Issue: 5; Other Information: DOI: 10.1063/1.2921791; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AMPLITUDES; ASYMPTOTIC SOLUTIONS; COLLISIONLESS PLASMA; DISTRIBUTION FUNCTIONS; DISTURBANCES; ELECTRONS; LANDAU DAMPING; NOISE; NONLINEAR PROBLEMS; ONE-DIMENSIONAL CALCULATIONS; PERTURBATION THEORY; PLASMA SIMULATION; SINGULARITY

Citation Formats

Belmont, G, Chust, T, Mottez, F, Hess, S, and Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique. Existence of non-Landau solutions for Langmuir waves. United States: N. p., 2008. Web. doi:10.1063/1.2921791.
Belmont, G, Chust, T, Mottez, F, Hess, S, & Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique. Existence of non-Landau solutions for Langmuir waves. United States. doi:10.1063/1.2921791.
Belmont, G, Chust, T, Mottez, F, Hess, S, and Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique. Thu . "Existence of non-Landau solutions for Langmuir waves". United States. doi:10.1063/1.2921791.
@article{osti_21120304,
title = {Existence of non-Landau solutions for Langmuir waves},
author = {Belmont, G and Chust, T and Mottez, F and Hess, S and Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique},
abstractNote = {The propagation of linear one dimensional (1D) Langmuir waves is reinvestigated using numerical simulations of a new type with very low noise. The dependence of the result on the initial conditions is shown. New solutions are exhibited, with properties different from Landau's, even in the asymptotic behavior, in particular with regard to the damping rate. These solutions are shown to demand a special preparation of the initial plasma perturbation, but in a way which is quite physical, without any singularity in the electron distribution function, contrary to the classical van Kampen's solutions. Using an original theoretical calculation, a simple analytical form is derived for the perturbed distribution function, which allows interpreting both the Landau and non-Landau solutions observed numerically. The numerical results presented and their interpretations are potentially important in several respects: 1) They outline that Landau solutions, for the 1D electrostatic problem in collisionless plasmas, are only a few among an infinite amount of others; even if the non-Landau solutions are much less probable, their existence provides a different view on the concept of kinetic damping and may suggest interpretations different from usual for the subsequent nonlinear effects; 2) they show that the shape of the initial perturbation {delta}f(v), and not only its amplitude, is important for the long time wave properties, both linear and nonlinear; 3) the existence of non-Landau solutions makes clear that the classical energy arguments cannot be fully universal as long as they allow deriving the Landau damping rate independently of the initial conditions; 4) the particle signature of Landau damping, different from the usual guess, should imply a change in our understanding of the role of the resonant particles.},
doi = {10.1063/1.2921791},
journal = {Physics of Plasmas},
issn = {1070-664X},
number = 5,
volume = 15,
place = {United States},
year = {2008},
month = {5}
}