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Title: Nonlinear beam generated plasma waves as a source for enhanced plasma and ion acoustic lines

Abstract

Observations by, for instance, the EISCAT Svalbard Radar (ESR) demonstrate that the symmetry of the naturally occurring ion line in the polar ionosphere can be broken by an enhanced, nonthermal, level of fluctuations (naturally enhanced ion-acoustic lines, NEIALs). It was in many cases found that the entire ion spectrum can be distorted, also with the appearance of a third line, corresponding to a propagation velocity significantly slower than the ion acoustic sound speed. It has been argued that selective decay of beam excited primary Langmuir waves can explain some phenomena similar to those observed. We consider a related model, suggesting that a primary nonlinear process can be an oscillating two-stream instability, generating a forced low frequency mode that does not obey any ion sound dispersion relation. At later times, the decay of Langmuir waves can give rise also to enhanced asymmetric ion lines. The analysis is based on numerical results, where the initial Langmuir waves are excited by a cold dilute electron beam. By this numerical approach, we can detect fine details of the physical processes, in particular, demonstrate a strong space-time intermittency of the electron waves in agreement with observations. Our code solves the full Vlasov equation for electronsmore » and ions, with the dynamics coupled through the electrostatic field derived from Poisson's equation. The analysis distinguishes the dynamics of the background and beam electrons. This distinction simplifies the analysis for the formulation of the weakly nonlinear analytical model for the oscillating two-stream instability. The results have general applications beyond their relevance for the ionospheric observations.« less

Authors:
 [1];  [2];  [3];  [4];  [5];  [6]
  1. University of Michigan, Space Research Building, 2455 Hayward Street, Ann Arbor, Michigan 48109-2143 (United States)
  2. Department of Physics, University of Oslo, Box 1048 Blindern, N-0316 Oslo (Norway)
  3. Institute of Theoretical Astrophysics, University of Oslo, Box 1029 Blindern, N-0315 Oslo (Norway)
  4. Norwegian Water Resources and Energy Directorate, Drammensveien 211, Postboks 5091 Majorstua, N-0301 Oslo (Norway)
  5. Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)
  6. Department of Physics, Linkoeping University, SE-58183 Linkoeping (Sweden)
Publication Date:
OSTI Identifier:
21537789
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 18; Journal Issue: 5; Other Information: DOI: 10.1063/1.3582084; (c) 2011 American Institute of Physics; Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BOLTZMANN-VLASOV EQUATION; ELECTRON BEAMS; FLUCTUATIONS; NONLINEAR PROBLEMS; PLASMA; PLASMA SIMULATION; PLASMA WAVES; POISSON EQUATION; TURBULENCE; TWO-STREAM INSTABILITY; BEAMS; DIFFERENTIAL EQUATIONS; EQUATIONS; INSTABILITY; LEPTON BEAMS; PARTIAL DIFFERENTIAL EQUATIONS; PARTICLE BEAMS; PLASMA INSTABILITY; PLASMA MICROINSTABILITIES; SIMULATION; VARIATIONS

Citation Formats

Daldorff, L K. S., Pecseli, H L, Trulsen, J K, Ulriksen, M I, Eliasson, B, and Stenflo, L. Nonlinear beam generated plasma waves as a source for enhanced plasma and ion acoustic lines. United States: N. p., 2011. Web. doi:10.1063/1.3582084.
Daldorff, L K. S., Pecseli, H L, Trulsen, J K, Ulriksen, M I, Eliasson, B, & Stenflo, L. Nonlinear beam generated plasma waves as a source for enhanced plasma and ion acoustic lines. United States. https://doi.org/10.1063/1.3582084
Daldorff, L K. S., Pecseli, H L, Trulsen, J K, Ulriksen, M I, Eliasson, B, and Stenflo, L. Sun . "Nonlinear beam generated plasma waves as a source for enhanced plasma and ion acoustic lines". United States. https://doi.org/10.1063/1.3582084.
@article{osti_21537789,
title = {Nonlinear beam generated plasma waves as a source for enhanced plasma and ion acoustic lines},
author = {Daldorff, L K. S. and Pecseli, H L and Trulsen, J K and Ulriksen, M I and Eliasson, B and Stenflo, L},
abstractNote = {Observations by, for instance, the EISCAT Svalbard Radar (ESR) demonstrate that the symmetry of the naturally occurring ion line in the polar ionosphere can be broken by an enhanced, nonthermal, level of fluctuations (naturally enhanced ion-acoustic lines, NEIALs). It was in many cases found that the entire ion spectrum can be distorted, also with the appearance of a third line, corresponding to a propagation velocity significantly slower than the ion acoustic sound speed. It has been argued that selective decay of beam excited primary Langmuir waves can explain some phenomena similar to those observed. We consider a related model, suggesting that a primary nonlinear process can be an oscillating two-stream instability, generating a forced low frequency mode that does not obey any ion sound dispersion relation. At later times, the decay of Langmuir waves can give rise also to enhanced asymmetric ion lines. The analysis is based on numerical results, where the initial Langmuir waves are excited by a cold dilute electron beam. By this numerical approach, we can detect fine details of the physical processes, in particular, demonstrate a strong space-time intermittency of the electron waves in agreement with observations. Our code solves the full Vlasov equation for electrons and ions, with the dynamics coupled through the electrostatic field derived from Poisson's equation. The analysis distinguishes the dynamics of the background and beam electrons. This distinction simplifies the analysis for the formulation of the weakly nonlinear analytical model for the oscillating two-stream instability. The results have general applications beyond their relevance for the ionospheric observations.},
doi = {10.1063/1.3582084},
url = {https://www.osti.gov/biblio/21537789}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 5,
volume = 18,
place = {United States},
year = {2011},
month = {5}
}