On Geometric and Dynamical Relationships Between Quasi-Separatrix Layers and Field Line Slippage
Thomas Chan (University of Glasgow)
Wednesday 11th March 15:00-16:00
Maths 311B
Abstract
Magnetic reconnection is a fundamental process that underpins many dynamical processes in the solar corona. A lot of research revolves around the location of reconnection in coronal active regions, and in 3D magnetic field configurations, one often uses magnetic topology to determine these regions, which require information along field lines. Quasi-separatrix layers (QSLs) are a highly important topological feature, which are defined as volumes in which field lines showcase high connectivity gradients, making them ideal locations for current sheet development and reconnection.
However, in turbulent plasma, which is prevalent in active regions, using topological features is not highly insightful, and we need to resort to local descriptions of reconnection. This is done using the magnetic slippage rate, which is characterised by the Lorentz force and field-aligned current gradients and relies only on the local information about the geometry of the field.
In this work, we combine global and local perspectives by establishing a quantitative connection between QSLs and the magnetic slippage rate. This is achieved through analytical investigations of sheared magnetic fields and MHD simulations of a nonlinear force-free (NLFF) model developed by Low and Lou. Our results demonstrate an underlying relationship between field line connectivity gradients and field line slippage. We further show that this correlation is governed by geometric characteristics of the magnetic field, particularly shears and twists, and provide a unified interpretation of reconnection using independent diagnostics.
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