Effect of guide field on three-dimensional electron shear flow instabilities in electron current sheets

Jain, Neeraj; Büchner, Jörg

doi:10.1017/s0022377815001257

Cited by 14 publications

(9 citation statements)

References 22 publications

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“…In general, an electron current sheet is unstable to tearing and non-tearing modes. For a finite guide field and L = d e , the growth rate of the fastest growing non-tearing mode is larger but comparable to that of the 2-D tearing mode (k z = 0) 25 . The power of the initial perturbation ∝ sin(πy/l y ) exp(−z 2 /2L 2 ) added to the equilibrium peaks for k z = 0 and k y d e = 0.628.…”

Section: Spreading Of Localized Magnetic Reconnectionmentioning

confidence: 89%

Spreading of magnetic reconnection by electron scale dispersive waves

Jain,

Buechner

2016

Preprint

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We show that on electron scales a patch of the localized magnetic reconnection spreads bi-directionally in a wave like fashion when an external guide-magnetic field in the direction of the electron current is present. The spreading is caused by the propagation of the flow induced and whistler wave modes away from the localized patch. For small guide fields, the spreading is asymmetric being faster in the direction of the electron flow. On increasing the guide field, the spreading becomes increasingly symmetric due to the dominance of the whistler group speed in determining the speed of the spreading. The wave-like spreading of reconnection causes the alternate formation of X-and O-points in the reconnection planes separated by half the wavelength of the reconnection wave.

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Section: Spreading Of Localized Magnetic Reconnectionmentioning

confidence: 89%

Spreading of magnetic reconnection by electron scale dispersive waves

Jain,

Buechner

2016

Preprint

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“…In the simulations, the half-thicknesses of the shear layers of the in-plane and out-of-plane electron flows are of the order of an electron inertial length. Ignoring the in- plane shear flows, the fastest growing mode feeding on the out-of-plane electron shear flow v z0 (x ) in the presence of a large guide magnetic field is non-tearing with a growth rate γ f ∼ 0.05 ω ce and wave numbers k y d e ∼ 10 and k z d e ∼ 1 16 . However, the simulations do not show any mode developing in the z-direction, i.e., k z = 0, suggesting no role of the instabilities feeding on out-of-plane electron shear flow.…”

Section: Discussionmentioning

confidence: 99%

Electron-magnetohydrodynamic simulations of electron scale current sheet dynamics in the Vineta.II guide field reconnection experiment

et al. 2017

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“…Otherwise non-tearing mode instabilities dominate. In recent eigen-value analysis of 3-D electron shear flow instabilities, we have shown that finite guide field makes the linear electron tearing mode instability sub-dominant even for the thin current sheets 14 .…”

Section: Introductionmentioning

confidence: 90%

“…8b shows that < k 2 y > remains greater than < k 2 z > throughout the evolution for strength of guide field in the range B g /B 0 =1-4. In the early phase this is because of k y > k z typical for the linearly unstable modes in case of finite guide fields 14 . This can be seen in Fig.…”

Section: Evolution Of Electron Shear Flow Instabilities In the Pmentioning

confidence: 99%

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Nonlinear evolution of electron shear flow instabilities in the presence of an external guide magnetic field

2017

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The dissipation mechanism by which the magnetic field reconnects in the presence of an external (guide) magnetic field in the direction of the main current is not well understood. In thin electron current sheets (half thickness close to an electron inertial length) formed in collisionless magnetic reconnection, electron shear flow instabilities are potential candidates for providing an anomalous dissipation mechanism which can break the frozen-in condition of the magnetic field affecting the structure and rate of reconnection. We present the results of investigations of the evolution of electron shear flow instabilities, from linear to nonlinear state, in guide field magnetic reconnection. The properties of the plasma turbulence resulting from the growth of the instability and their dependence on the strength of the guide field are studied. For this sake, we utilize three dimensional electron-magnetohydrodynamic simulations of electron current sheets. We show that, unlike the case of current sheets selfconsistently embedded in anti-parallel magnetic fields, the evolution of thin electron current sheets in the presence of a finite external guide field (equal to the asymptotic value of the reconnecting magnetic field or larger) is dominated by high wave number non-tearing mode instabilities. The latter cause the development of, first, a wavy structure of the current sheet. The turbulence, developed later, consists of current filaments and electron flow vortices. As a result of the nonlinear evolution of the instability, the current sheet broadens simultaneously with its flattening in the central region mimicking a viscous-like turbulent dissipation. Later, the flattened current sheet bifurcates. During the time of the bifurcation, the rate of the change of the mean electron flow velocity is proportional to the magnitude of the flow velocity, suggesting a resistive-like dissipation. The turbulence energy cascades to shorter wavelengths preferentially in the direction perpendicular to the guide magnetic field.The degree of anisotropy of the turbulence was found to increase with the increasing strength of the guide field.

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Effect of guide field on three-dimensional electron shear flow instabilities in electron current sheets

Cited by 14 publications

References 22 publications

Spreading of magnetic reconnection by electron scale dispersive waves

Spreading of magnetic reconnection by electron scale dispersive waves

Electron-magnetohydrodynamic simulations of electron scale current sheet dynamics in the Vineta.II guide field reconnection experiment

Nonlinear evolution of electron shear flow instabilities in the presence of an external guide magnetic field

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