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Accueil > Séminaires et conférences > Séminaires, soutenances de thèses et HDR précédents > 2010 > Séminaires 2010 > Le jeudi 7 octobre à 14h

Le jeudi 7 octobre à 14h

Amitava Bhattacharjee (Center for Integrated Computation and Analysis of Reconnection and Turbulence,
Space Science Center, University of New Hampshire)

Le jeudi 7 octobre à 14h (salle de réunion du CPHT)

Onset of Fast Reconnection Mediated by the Plasmoid Instability in Astrophysical Systems

Thin current sheets in systems of large size that exceed a critical value of the Lundquist number are unstable to a super-Alfvénic tearing instability, referred to hereafter as the plasmoid instability. The scaling of the growth rate of the most rapidly growing plasmoid instability with respect to the Lundquist number is shown to follow from the classical dispersion relation for tearing modes. As a result of this instability, the system realizes a nonlinear reconnection rate that appears to be weakly dependent on the Lundquist number, and larger than the Sweet-Parker rate by nearly an order of magnitude (for the range of Lundquist numbers considered).The results from the largest 2D Hall MHD reconnection is reported, demonstrating that the plasmoid instability facilitates the onset of fast reconnection. This regime of fast reconnection is realizable in a dynamic and highly unstable thin current sheet, without requiring the current sheet to be turbulent. Implications for particle acceleration will be discussed, including relevance to Cluster observations.

Tutelles : CNRS Ecole Polytechnique Sorbonne Université Université Paris Sud Observatoire de Paris Convention : CEA
©2009-2019 Laboratoire de Physique des Plasmas (LPP)

Mentions légales
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)