Structure-driven nonlinear instability as the origin of the explosive reconnection dynamics in resistive double tearing modes

M. Janvier, Y. Kishimoto, J. Q. Li

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    Abstract

    The onset of abrupt magnetic reconnection events, observed in the nonlinear evolution of double tearing modes (DTM), is investigated via reduced resistive magnetohydrodynamic simulations. We have identified the critical threshold for the parameters characterizing the linear DTM stability leading to the bifurcation to the explosive dynamics. A new type of secondary instability is discovered that is excited once the magnetic islands on each rational surface reach a critical structure characterized here by the width and the angle rating their triangularization. This new instability is an island structure-driven nonlinear instability, identified as the trigger of the subsequent nonlinear dynamics which couples flow and flux perturbations. This instability only weakly depends on resistivity.

    Original languageEnglish
    Article number195001
    Number of pages5
    JournalPhysical Review Letters
    Volume107
    Issue number19
    DOIs
    Publication statusPublished - 31 Oct 2011

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