Magnetic reconnection and stochastic plasmoid chains in high-Lundquist-number plasmas

Aug, 2011
5 pages
Published in:
  • Phys.Plasmas 19 (2012) 042303
e-Print:

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Abstract: (arXiv)
A numerical study of magnetic reconnection in the large-Lundquist-number (SS), plasmoid-dominated regime is carried out for SS up to 10710^7. The theoretical model of Uzdensky {\it et al.} [Phys. Rev. Lett. {\bf 105}, 235002 (2010)] is confirmed and partially amended. The normalized reconnection rate is \normEeff\sim 0.02 independently of SS for S104S\gg10^4. The plasmoid flux (Ψ\Psi) and half-width (wxw_x) distribution functions scale as f(Ψ)Ψ2f(\Psi)\sim \Psi^{-2} and f(wx)wx2f(w_x)\sim w_x^{-2}. The joint distribution of Ψ\Psi and wxw_x shows that plasmoids populate a triangular region wxΨ/B0w_x\gtrsim\Psi/B_0, where B0B_0 is the reconnecting field. It is argued that this feature is due to plasmoid coalescence. Macroscopic 'monster' plasmoids with wx10w_x\sim 10% of the system size are shown to emerge in just a few Alfv\'en times, independently of SS, suggesting that large disruptive events are an inevitable feature of large-SS reconnection.