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Accueil > Séminaires et conférences > Séminaires, soutenances de thèses et HDR précédents > 2016 > Séminaires 2016 > Le mercredi 21 Septembre à 10h

Le mercredi 21 Septembre à 10h

W. H. Matthaeus, University of Delaware, US
Titre : Heating of protons and electrons in intermittent plasma turbulence : theory and simulation
Quand : Le mercredi 21 Septembre à 10h
Lieu : Jussieu (LPP, Tour 24-34, 5eme étage)

Résumé :Theoretical analysis along with particle-in-cell simulations of kinetic plasma turbulence reveals a connection between the strength of cascade, the total heating rate, and the partitioning of dissipated energy into proton heating and electron heating. First, we find that a von Karman scaling of the cascade rate extended to the MHD regime explains the total heating across several families of simulations. Next, the proton to electron heating ratio increases in proportion to total heating, as a stronger cascade exposes the protons to steeper gradients, which in turn increase proton response, leaving less cascaded energy for electron heating. This effect may be estimated by postulating a dependence on the ratio of gyroperiod to nonlinear turnover time at the ion kinetic scales. The proposed scaling is found to be consistent with simulations. Combining the ideas of von Karman scaling and the scaling of variation of proton to electron heating, one arrives at a simple prediction for both proton and electron heating. Further analysis reveals that heating is concentrated in space, typically near current structures but more closely associated with velocity stresses including vorticity. An overall picture emerges in which intermittent turbulent dissipation, preferentially associated with structures, can be understood in both MHD and in Vlasov theory.

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