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Kelvin-Helmholtz instability in a current-vortex sheet at a 3D magnetic null.

Wyper, P. and Pontin, D. (2013) 'Kelvin-Helmholtz instability in a current-vortex sheet at a 3D magnetic null.', Physics of plasmas., 20 (3). 032117.


We report here, for the first time, an observed instability of a Kelvin-Helmholtz nature occurring in a fully three-dimensional (3D) current-vortex sheet at the fan plane of a 3D magnetic null point. The current-vortex layer forms self-consistently in response to foot point driving around the spine lines of the null. The layer first becomes unstable at an intermediate distance from the null point, with the instability being characterized by a rippling of the fan surface and a filamentation of the current density and vorticity in the shear layer. Owing to the 3D geometry of the shear layer, a branching of the current filaments and vortices is observed. The instability results in a mixing of plasma between the two topologically distinct regions of magnetic flux on either side of the fan separatrix surface, as flux is reconnected across this surface. We make a preliminary investigation of the scaling of the system with the dissipation parameters. Our results indicate that the fan plane separatrix surface is an ideal candidate for the formation of current-vortex sheets in complex magnetic fields and, therefore, the enhanced heating and connectivity change associated with the instabilities of such layers.

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Publisher statement:© 2013 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Wyper, P. & Pontin, D. (2013). Kelvin-Helmholtz instability in a current-vortex sheet at a 3D magnetic null. Physics of Plasmas 20(3): 032117 and may be found at
Date accepted:12 March 2013
Date deposited:29 March 2017
Date of first online publication:29 March 2013
Date first made open access:No date available

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