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Accueil > Séminaires et conférences > Séminaires, soutenances de thèses et HDR précédents > 2012 > Séminaires 2012 > Le jeudi 1er mars à 11h

Le jeudi 1er mars à 11h

Constraints on fluid models for the slow dynamics of collisionless space plasmas.

T. Passot, P.L. Sulem and P. Hunana
Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d’Azur

A Saint-Maur, salle de réunion

Fluid models are not only more tractable than kinetic ones to simulate three-dimensional turbulence in space plasmas, but also provide a convenient framework for theoretical insight. Collisionless plasmas are however not readily amenable to a standard MHD description, especially in directions parallel to the ambient magnetic field. Several types of closures for the fluid moment hierarchy have been developed, that usually neglect some elements of the various fluid moment tensors, but can nevertheless keep into account important dissipative effects originating from the linear Landau damping. It is indeed very important to capture as accurately as possible the linear dynamics that plays a major role at small scales in such plasmas. It will be shown that in order to accurately reproduce the linear properties of the "slow dynamics" regime, and in particular the mirror modes, an almost complete description of the heat flux tensor is needed. Two models will be discussed, pointing out their achievements and limitations.
One is limited to relatively large scales, while the other extends to sub-ionic scales. Simulations of the development of temperature anisotropy and their limitations by micro-instabilities, based on the latter model, will also be reported.


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Tutelles : CNRS Ecole Polytechnique Sorbonne Université Université Paris Sud Observatoire de Paris Convention : CEA
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Hébergeur : Laboratoire de Physique des Plasmas, Ecole Polytechnique route de Saclay F-91128 PALAISEAU CEDEX
Directeur de la publication : Pascal Chabert (Directeur)