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Article Dans Une Revue Journal of Plasma Physics Année : 2022

Microscopic scales of linear tearing modes: a tutorial on boundary layer theory for magnetic reconnection

Résumé

We revise in detail and in a pedagogical way the analysis of the boundary layer theory of warm tearing modes in slab, reduced MHD, when magnetic reconnection is driven by electron inertia and/or resistivity, and ion-sound Larmor radius effects are included. By comparison with the numerical solution of the corresponding eigenvalue problem we interpret these results by means of a heuristic approach, which in the warm electron regime we show to be in general not feasible without knowledge of the scaling of the gradient of the magnetic flux function, differently from what happens in the cold-eletcron regimes. We put in evidence a non-trivial relation between the first derivative of the magnetic flux function and of the velocity parallel to the neutral line, evaluated in its proximity, by thus providing insight to the multiple boundary layer analysis that Pegoraro & Schep (1986) first showed to be required in warm-tearing regimes. In this way we also suggest and justify a general operational definition of the reconnecting layer width and we discuss the linear appearence of microscopic scales related to the gradients of the eigenfunctions of the tearing modes.
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Dates et versions

hal-03809727 , version 1 (10-10-2022)
hal-03809727 , version 2 (27-06-2023)

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H. Betar, D. Del Sarto, M. Ottaviani, A. Ghizzo. Microscopic scales of linear tearing modes: a tutorial on boundary layer theory for magnetic reconnection. Journal of Plasma Physics, 2022, 88 (6), pp.925880601. ⟨10.1017/S0022377822001088⟩. ⟨hal-03809727v2⟩
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