Wood, TS, Hollerbach, R and Lyutikov, M (2014) Density-shear instability in electron magneto-hydrodynamics. Physics of Plasmas, 21 (5). ISSN 1070-664X
Abstract
We discuss a novel instability in inertia-less electron magneto-hydrodynamics (EMHD), which arises from a combination of electron velocity shear and electron density gradients. The unstable modes have a lengthscale longer than the transverse density scale, and a growth-rate of the order of the inverse Hall timescale. We suggest that this density-shear instability may be of importance in magnetic reconnection regions on scales smaller than the ion skin depth, and in neutron star crusts. We demonstrate that the so-called Hall drift instability, previously argued to be relevant in neutron star crusts, is a resistive tearing instability rather than an instability of the Hall term itself. We argue that the density-shear instability is of greater significance in neutron stars than the tearing instability, because it generally has a faster growth-rate and is less sensitive to geometry and boundary conditions. We prove that, for uniform electron density, EMHD is "at least as stable" as regular, incompressible MHD, in the sense that any field configuration that is stable in MHD is also stable in EMHD. We present a connection between the density-shear instability in EMHD and the magneto-buoyancy instability in anelastic MHD.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | Copyright (2014) 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 Wood, TS, Hollerbach, R and Lyutikov, M (2014) Density-shear instability in electron magneto-hydrodynamics. Physics of Plasmas, 21, 5, ISSN 1070-664X and may be found at http://dx.doi.org/10.1063/1.4879810. |
Keywords: | Magnetic fields; Magnetohydrodynamics; Neutron star crust; Boundary value problems; Macroinstabilities |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Mathematics (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 24 Jul 2014 11:03 |
Last Modified: | 21 Jan 2018 21:53 |
Published Version: | http://dx.doi.org/10.1063/1.4879810 |
Status: | Published |
Publisher: | American Institute of Physics (AIP) |
Identification Number: | 10.1063/1.4879810 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:79757 |