54th Annual Meeting of the APS Division of Plasma Physics
Volume 57, Number 12
Monday–Friday, October 29–November 2 2012;
Providence, Rhode Island
Session BI2: Laboratory Plasma Astrophysics I
9:30 AM–12:30 PM,
Monday, October 29, 2012
Room: Ballroom DE
Chair: Hantao Ji, Princeton Plasma Physics Laboratory
Abstract ID: BAPS.2012.DPP.BI2.5
Abstract: BI2.00005 : Plasmoid Instability in High-Lundquist-Number Magnetic Reconnection
11:30 AM–12:00 PM
Preview Abstract
Abstract
Author:
Yi-Min Huang
(Center for Integrated Computation and Analysis of Reconnection and Turbulence and Center for Magnetic Self-Organization, University of New Hampshire)
Our understanding of magnetic reconnection in resistive magnetohydrodynamics
has gone through a fundamental change in recent years. The conventional
wisdom is that magnetic reconnection mediated by resistivity is slow
in high Lundquist ($S$) plasmas, due to the $S^{-1/2}$ scaling of
reconnection rate predicted by the classical Sweet-Parker theory.
However, recent studies showed that when $S$ exceeds a critical value
$\sim10^{4}$, the Sweet-Parker current sheet is unstable to a super-Alfvenic
plasmoid instability, with a growth rate that increases with $S$ [1].
Consequently, the reconnection layer changes to a chain of plasmoids
connected by secondary current sheets that, in turn, may become unstable
again. Eventually the reconnection layer will tend to a statistical
steady state governed by complex dynamics of plasmoid formation and
plasmoid loss due to advection and coalescence. The averaged reconnection
rate in this regime is nearly independent of $S$ [2,3],
and the distribution function $f(\psi)$ of magnetic fluxes $\psi$
in plasmoids follows a power-law $f\sim\psi^{-1}$. When Hall effects
are included, the plasmoid instability may trigger onset of Hall reconnection
even when the conventional criterion for onset is not satisfied. In
addition to the usual single X-point topology of Hall reconnection,
our large-scale resistive Hall MHD simulations reveal a novel intermediate
regime, where formation of new plasmoids is observed after onset of
Hall reconnection [4]. Qualitatively similar results
have also been found when resistivity is replaced by hyper-resistivity.
Our findings suggest that plasmoid formation may be a generic feature
of magnetic reconnection in large systems, regardless of the mechanism
of breaking the frozen-in condition. (In collaboration with A. Bhattacharjee
and B. P. Sullivan).\\[4pt]
[1] N. F. Loureiro, A. A. Schekochihin, and S. C. Cowley, Phys. Plasmas 14, 100703 (2007).\\[0pt]
[2] A. Bhattacharjee, Y.-M. Huang, H. Yang, and B. Rogers, Phys. Plasmas 16, 112102 (2009).\\[0pt]
[3] Y.-M. Huang and A. Bhattacharjee, Phys. Plasmas 17, 062104 (2010).\\[0pt]
[4] Y.-M. Huang, A. Bhattacharjee, and B. P. Sullivan, Phys. Plasmas 18, 072109 (2011).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2012.DPP.BI2.5