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Title: LANGMUIR WAVE DECAY IN INHOMOGENEOUS SOLAR WIND PLASMAS: SIMULATION RESULTS

Abstract

Langmuir turbulence excited by electron flows in solar wind plasmas is studied on the basis of numerical simulations. In particular, nonlinear wave decay processes involving ion-sound (IS) waves are considered in order to understand their dependence on external long-wavelength plasma density fluctuations. In the presence of inhomogeneities, it is shown that the decay processes are localized in space and, due to the differences between the group velocities of Langmuir and IS waves, their duration is limited so that a full nonlinear saturation cannot be achieved. The reflection and the scattering of Langmuir wave packets on the ambient and randomly varying density fluctuations lead to crucial effects impacting the development of the IS wave spectrum. Notably, beatings between forward propagating Langmuir waves and reflected ones result in the parametric generation of waves of noticeable amplitudes and in the amplification of IS waves. These processes, repeated at different space locations, form a series of cascades of wave energy transfer, similar to those studied in the frame of weak turbulence theory. The dynamics of such a cascading mechanism and its influence on the acceleration of the most energetic part of the electron beam are studied. Finally, the role of the decay processes in the shapingmore » of the profiles of the Langmuir wave packets is discussed, and the waveforms calculated are compared with those observed recently on board the spacecraft Solar TErrestrial RElations Observatory and WIND.« less

Authors:
 [1];  [2]
  1. Laboratoire de Physique des Plasmas, Ecole Polytechnique, F-91128 Palaiseau Cedex (France)
  2. IZMIRAN, Troitsk, 142190, Moscow (Russian Federation)
Publication Date:
OSTI Identifier:
22525545
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 809; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; ENERGY TRANSFER; FLUCTUATIONS; IONS; NONLINEAR PROBLEMS; PLASMA DENSITY; PLASMA SIMULATION; SOLAR ELECTRONS; SOLAR WIND; SOUND WAVES; SPACE; SPACE VEHICLES; SUN; TURBULENCE; WAVE FORMS; WAVE PACKETS

Citation Formats

Krafft, C., Volokitin, A. S., and Krasnoselskikh, V. V., E-mail: catherine.krafft@u-psud.fr. LANGMUIR WAVE DECAY IN INHOMOGENEOUS SOLAR WIND PLASMAS: SIMULATION RESULTS. United States: N. p., 2015. Web. doi:10.1088/0004-637X/809/2/176.
Krafft, C., Volokitin, A. S., & Krasnoselskikh, V. V., E-mail: catherine.krafft@u-psud.fr. LANGMUIR WAVE DECAY IN INHOMOGENEOUS SOLAR WIND PLASMAS: SIMULATION RESULTS. United States. https://doi.org/10.1088/0004-637X/809/2/176
Krafft, C., Volokitin, A. S., and Krasnoselskikh, V. V., E-mail: catherine.krafft@u-psud.fr. 2015. "LANGMUIR WAVE DECAY IN INHOMOGENEOUS SOLAR WIND PLASMAS: SIMULATION RESULTS". United States. https://doi.org/10.1088/0004-637X/809/2/176.
@article{osti_22525545,
title = {LANGMUIR WAVE DECAY IN INHOMOGENEOUS SOLAR WIND PLASMAS: SIMULATION RESULTS},
author = {Krafft, C. and Volokitin, A. S. and Krasnoselskikh, V. V., E-mail: catherine.krafft@u-psud.fr},
abstractNote = {Langmuir turbulence excited by electron flows in solar wind plasmas is studied on the basis of numerical simulations. In particular, nonlinear wave decay processes involving ion-sound (IS) waves are considered in order to understand their dependence on external long-wavelength plasma density fluctuations. In the presence of inhomogeneities, it is shown that the decay processes are localized in space and, due to the differences between the group velocities of Langmuir and IS waves, their duration is limited so that a full nonlinear saturation cannot be achieved. The reflection and the scattering of Langmuir wave packets on the ambient and randomly varying density fluctuations lead to crucial effects impacting the development of the IS wave spectrum. Notably, beatings between forward propagating Langmuir waves and reflected ones result in the parametric generation of waves of noticeable amplitudes and in the amplification of IS waves. These processes, repeated at different space locations, form a series of cascades of wave energy transfer, similar to those studied in the frame of weak turbulence theory. The dynamics of such a cascading mechanism and its influence on the acceleration of the most energetic part of the electron beam are studied. Finally, the role of the decay processes in the shaping of the profiles of the Langmuir wave packets is discussed, and the waveforms calculated are compared with those observed recently on board the spacecraft Solar TErrestrial RElations Observatory and WIND.},
doi = {10.1088/0004-637X/809/2/176},
url = {https://www.osti.gov/biblio/22525545}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 809,
place = {United States},
year = {Thu Aug 20 00:00:00 EDT 2015},
month = {Thu Aug 20 00:00:00 EDT 2015}
}