A theory of magnetic field line slippage

David MacTaggart (University of Glasgow)

Wednesday 26th November 15:00-16:00
Maths 311B

Abstract

Magnetic reconnection is a fundamental property of plasmas with many applications. The theoretical treatment of magnetic reconnection in three dimensions has mainly focussed on two aspects: (1) the possible locations of reconnection via studies of magnetic topology (e.g. magnetic skeletons and quasi-separatrix layers) and (2) the rate of change of magnetic flux (the reconnection rate) determined using the so-called theory of General Magnetic Reconnection (GMR). These approaches are global methods, in the sense that they require information about all or a large part of the magnetic field under study. Whilst these approaches have proved to be very successful, there is some debate about how they may be extended to turbulent plasmas. In this talk, I will present a complementary theory of reconnection in terms of field line slippage which, unlike its predecessors, is a local theory, i.e. it only requires information in a small neighbourhood about a point in space where calculations are performed. This theory is applicable in both turbulent and laminar plasmas and also provides information about how magnetic topology connects to “geometric” properties of the magnetic field, such as the Lorentz force and field-aligned current. Examples of the theory will be provided in applications to the Sun and the Earth’s magnetosphere. 

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