Dynamic topology and flux rope evolution during non-linear tearing of 3D null point current sheets

In this work, the dynamic magnetic field within a tearing-unstable three-dimensional current sheet about a magnetic null point is described in detail. We focus on the evolution of the magnetic null points and flux ropes that are formed during the tearing process. Generally, we find that both magneti...

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Bibliographic Details
Published in:Physics of plasmas 2014-10, Vol.21 (10)
Main Authors: Wyper, P. F., Pontin, D. I.
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BIFURCATION
Bifurcations
Braiding
Current sheets
CURRENTS
Evolution
Fluid dynamics
Fluid flow
HYDROMAGNETIC WAVES
Kinking
LAYERS
Magnetic fields
Magnetic flux
Magnetohydrodynamic waves
Magnetohydrodynamics
Outflow
Plasma physics
Tearing
THREE-DIMENSIONAL CALCULATIONS
TOPOLOGY
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Summary:In this work, the dynamic magnetic field within a tearing-unstable three-dimensional current sheet about a magnetic null point is described in detail. We focus on the evolution of the magnetic null points and flux ropes that are formed during the tearing process. Generally, we find that both magnetic structures are created prolifically within the layer and are non-trivially related. We examine how nulls are created and annihilated during bifurcation processes, and describe how they evolve within the current layer. The type of null bifurcation first observed is associated with the formation of pairs of flux ropes within the current layer. We also find that new nulls form within these flux ropes, both following internal reconnection and as adjacent flux ropes interact. The flux ropes exhibit a complex evolution, driven by a combination of ideal kinking and their interaction with the outflow jets from the main layer. The finite size of the unstable layer also allows us to consider the wider effects of flux rope generation. We find that the unstable current layer acts as a source of torsional magnetohydrodynamic waves and dynamic braiding of magnetic fields. The implications of these results to several areas of heliophysics are discussed.
ISSN:1070-664X
1089-7674
DOI:10.1063/1.4896060