[Observations et modélisation théorique de la turbulence à lʼéchelle électronique dans le vent solaire]
La turbulence aux échelles magnétohydrodynamique (MHD) dans le vent solaire a été étudiée pendant plus de trois décennies, au moyen dʼanalyses de données, de modélisations théoriques et de simulations numériques. Cependant, les plus petites échelles nʼont pas été explorées jusquʼà très récemment. Ici, nous passons en revue les résultats récents sur la cascade et la dissipation de la turbulence du vent solaire à lʼéchelle des électrons. Grâce aux données à haute résolution temporelle des champs magnétique et électrique des satellites Cluster, nous avons obtenu les spectres de la turbulence jusquʼà 100 Hz (dans le référentiel du satellite) et avons mis en évidence une zone de dissipation dʼénergie autour de la fréquence correspondant à lʼéchelle de giration des électrons. Avant sa dissipation, lʼénergie subit deux cascades : une cascade classique à la Kolmogorov avec une loi dʼéchelle en dessus de lʼéchelle de giration des protons, et une nouvelle cascade en aux échelles sub-protoniques jusquʼà lʼ échelle électronique. Au-dessus le spectre a une loi de puissance plus pentue en jusquʼà la limite dʼobservation donnée par le niveau de bruit de lʼinstrument. La résolution numérique des équations linéaires de Maxwell–Vlasov combinées aux récentes prédictions de la théorique Gyrocinétique, montrent que ces résultats sont conformes à un scénario de cascade quasi-2D suivant le mode dʼAlfvén cinétique (KAW). Une analyse plus récente dʼun autre jeu de données, où les séparations de cluster étaient de , nous a permis dʼexplorer les échelles sous-proton en utilisant la technique k-filtering, et de confirmer la nature quasi-2D de la turbulence à ces échelles-là.
Turbulence at MagnetoHydroDynamics (MHD) scales in the solar wind has been studied for more than three decades, using data analysis, theoretical and numerical modeling. However, smaller scales have not been explored until very recently. Here, we review recent results on the first observation of cascade and dissipation of the solar wind turbulence at the electron scales. Thanks to the high resolution magnetic and electric field data of the Cluster spacecraft, we computed the spectra of turbulence up to (in the spacecraft reference frame) and found evidence of energy dissipation around the Doppler-shifted electron gyroscale . Before its dissipation, the energy is shown to undergo two cascades: a Kolmogorov-like cascade with a scaling above the proton gyroscale, and a new cascade at the sub-proton and electron gyroscales. Above the spectrum has a steeper power law down to the noise level of the instrument. Solving numerically the linear Maxwell–Vlasov equations combined with recent theoretical predictions of the Gyro-Kinetic theory, we show that the present results are consistent with a scenario of a quasi-two-dimensional cascade into Kinetic Alfvén modes (KAW). New analyses of other data sets, where the Cluster separation (of about ) allowed us to explore the sub-proton scales using the k-filtering technique, and to confirm the 2D nature of the turbulence at those scales.
Mot clés : Vent solaire, Turbulence, Dissipation, Cluster, Chauffage
Fouad Sahraoui 1 ; Melvyn L. Goldstein 2 ; K. Abdul-Kader 1 ; Gérard Belmont 1 ; Laurence Rezeau 1, 3 ; Patrick Robert 1 ; Patrick Canu 1
@article{CRPHYS_2011__12_2_132_0,
author = {Fouad Sahraoui and Melvyn L. Goldstein and K. Abdul-Kader and G\'erard Belmont and Laurence Rezeau and Patrick Robert and Patrick Canu},
title = {Observation and theoretical modeling of electron scale solar wind turbulence},
journal = {Comptes Rendus. Physique},
pages = {132--140},
publisher = {Elsevier},
volume = {12},
number = {2},
year = {2011},
doi = {10.1016/j.crhy.2010.11.008},
language = {en},
}
TY - JOUR AU - Fouad Sahraoui AU - Melvyn L. Goldstein AU - K. Abdul-Kader AU - Gérard Belmont AU - Laurence Rezeau AU - Patrick Robert AU - Patrick Canu TI - Observation and theoretical modeling of electron scale solar wind turbulence JO - Comptes Rendus. Physique PY - 2011 SP - 132 EP - 140 VL - 12 IS - 2 PB - Elsevier DO - 10.1016/j.crhy.2010.11.008 LA - en ID - CRPHYS_2011__12_2_132_0 ER -
%0 Journal Article %A Fouad Sahraoui %A Melvyn L. Goldstein %A K. Abdul-Kader %A Gérard Belmont %A Laurence Rezeau %A Patrick Robert %A Patrick Canu %T Observation and theoretical modeling of electron scale solar wind turbulence %J Comptes Rendus. Physique %D 2011 %P 132-140 %V 12 %N 2 %I Elsevier %R 10.1016/j.crhy.2010.11.008 %G en %F CRPHYS_2011__12_2_132_0
Fouad Sahraoui; Melvyn L. Goldstein; K. Abdul-Kader; Gérard Belmont; Laurence Rezeau; Patrick Robert; Patrick Canu. Observation and theoretical modeling of electron scale solar wind turbulence. Comptes Rendus. Physique, Volume 12 (2011) no. 2, pp. 132-140. doi : 10.1016/j.crhy.2010.11.008. https://comptes-rendus.academie-sciences.fr/physique/articles/10.1016/j.crhy.2010.11.008/
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