On a plasma sheath separating regions of oppositely directed magnetic field

Harris, Edward F.

doi:10.1007/bf02733547

Cited by 1,217 publications

(907 citation statements)

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“…The simulation is initialized with a Harris 18 34 was employed to suppress spurious features in the spectrum from the non-periodic boundary conditions. Finally, the reduced spectrum B z (k x ,k y ) corresponds to a sum over k z .…”

Section: Methodsmentioning

confidence: 99%

“…These capabilities have permitted a series of simulations using over 10 12 computational particles, nearly 10 3 larger than previous two-dimensional (2D) studies 5 . The case described here is initialized with a Harris 18 current sheet, with magnetic field B = B x0 tanh(z/λ)e x + B y0 e y where e x and e y are unit vectors, λ = d i is the initial half-thickness, d i is an ion inertial length, B y0 = B x0 is a uniform guide field, the ion to electron mass ratio is m i /m e = 100 and further details regarding the set-up are given in the Methods section.…”

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confidence: 99%

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Role of electron physics in the development of turbulent magnetic reconnection in collisionless plasmas

et al. 2011

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Magnetic reconnection releases energy explosively as field lines break and reconnect in plasmas ranging from the Earth's magnetosphere to solar eruptions and astrophysical applications. Collisionless kinetic simulations have shown that this process involves both ion and electron kinetic-scale features, with electron current layers forming nonlinearly during the onset phase and playing an important role in enabling field lines to break 1-4 . In larger two-dimensional studies, these electron current layers become highly extended, which can trigger the formation of secondary magnetic islands 5-10 , but the influence of realistic three-dimensional dynamics remains poorly understood. Here we show that, for the most common type of reconnection layer with a finite guide field, the three-dimensional evolution is dominated by the formation and interaction of helical magnetic structures known as flux ropes. In contrast to previous theories 11 , the majority of flux ropes are produced by secondary instabilities within the electron layers. New flux ropes spontaneously appear within these layers, leading to a turbulent evolution where electron physics plays a central role.Thin current layers are the preferred locations for magnetic reconnection to develop. The most common configuration in nature is guide-field geometry, where the rotation of magnetic field across the layer is less than 180 • . Present theoretical ideas of how reconnection proceeds in these configurations are deeply rooted in early analytical work 11 that, if correct, would imply a direct transition to three-dimensional (3D) turbulence due to a broad spectrum of interacting tearing instabilities. At the core of this idea is the notion that a spectrum of tearing instabilities develops across the initial current sheet for perturbations satisfying the local resonance condition. As these modes grow, the resulting magnetic islands would overlap, leading to stochastic magnetic-field lines and a turbulent evolution. Recently, this type of scenario was proposed as a mechanism for accelerating energetic particles during reconnection 12 . Similar ideas for generating turbulence have been studied in fusion plasmas 13 using resistive magnetohydrodynamics (MHD) and two-fluid 14 models. Alternatively, other researchers have imposed turbulent fluctuations within MHD models in an attempt to understand the consequences 15 . In either case, these results are not applicable to the highly collisionless environment of the magnetosphere, where reconnection is initiated within kinetic ion-scale current layers. The ability to study the self-consistent generation of turbulence during magnetic reconnection with first-principles 3D simulations has only become feasible in the past year.1 Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA, 2 University of California San Diego, La Jolla, California 92093, USA. *e-mail: daughton@lanl.gov. tearing instability gives rise to flux ropes as illustrated by an isosurface of the particle density coloured by the magnitude of the curr...

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

Role of electron physics in the development of turbulent magnetic reconnection in collisionless plasmas

et al. 2011

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“…[4] According to Lembege and Pellat [1982] and a more general analysis (Schindler [2007], see in particular, equation (10.240)), the sufficient stability condition for a tearing mode with the wavenumber k in a tail current sheet, which is locally described by a modified Harris equilibrium [Harris, 1962], can be written in the form…”

Section: Lembege-pellat Stability Condition and Flux Tube Volume Formmentioning

confidence: 99%

Tearing stability of a multiscale magnetotail current sheet

Sitnov

Schindler

2010

Geophysical Research Letters

152

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The sufficient stability criterion of the collisionless ion tearing mode in the magnetotail current sheet, which was first obtained by Lembege and Pellat in 1982, is considered. For many conventional 2D current sheet equilibria, this criterion is satisfied within the WKB approximation, which is commonly interpreted as stability of those equilibria with respect to tearing. However, this is not necessarily the case for equilibria with more than two characteristic spatial scales. An example for substantial tearing destabilization of an equilibrium with accumulation of the magnetic flux at the tailward end of a thin current sheet is presented. Similar equilibria are reported in Geotail and THEMIS observations prior to onsets of magnetospheric substorms and dipolarization fronts associated with bursty bulk flows.

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“…For the initial state, we adopt a periodic-double plasma sheet model in Harris equilibrium [Harris, 1962] …”

Section: Simulation Model and Resultsmentioning

confidence: 99%

A three‐dimensional hybrid simulation of magnetic reconnection

Nakamura

Fujimoto

1998

Geophysical Research Letters

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Abstract.We study magnetic reconnection in the magnetotail by a 3-D hybrid simulation (ion particle, charge neutralizing massless electron fluid). Magnetic reconnection is initiated by putting anomalous resistivity localized in the plasma sheet. The resistive region is set up to have a finite dawn-dusk extent so that 3-D effects in the presence of ion particle dynamics are studied. Indeed, in the course of reconnection, plasma flow pattern and magnetic field configuration show highly asymmetric features in the dawn-dusk direction due to ion kinetic responses. The initial dawn-to-dusk ion current is disrupted on the dawnside of the diffusion region, requiring electrons to flow into the diffusion region from the duskside of it to support the cross-tail current, resulting in dawnward bending of field lines prior to reconnection. In contrast, reconnected field lines are transported by the reconnection jet which has substantial duskward flow component and eventually bend duskward.

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On a plasma sheath separating regions of oppositely directed magnetic field

Cited by 1,217 publications

References 2 publications

Role of electron physics in the development of turbulent magnetic reconnection in collisionless plasmas

Role of electron physics in the development of turbulent magnetic reconnection in collisionless plasmas

Tearing stability of a multiscale magnetotail current sheet

A three‐dimensional hybrid simulation of magnetic reconnection

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