Identification of the Electron-Diffusion Region during Magnetic Reconnection in a Laboratory Plasma

Ren, Y.; Yamada, Masaaki; Ji, Hantao; Gerhardt, S. P.; Kulsrud, Russell M.

doi:10.1103/physrevlett.101.085003

Cited by 64 publications

(53 citation statements)

References 30 publications

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“…Equation (32) indicates that the mass ratio of ion and electron plays an important role in determining the critical thickness [37]. The above crude estimation is also comparable with experimental observations [37,38].…”

Section: Subcritical Bifurcation Of the Cssupporting

confidence: 75%

Onset of fast magnetic reconnection via subcritical bifurcation

Guo

Wang

2015

Front. Phys.

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Citation:Guo Z and Wang X (2015) Onset of fast magnetic reconnection via subcritical bifurcation. Front. Phys. 3:18. doi: 10.3389/fphy.2015.00018 Onset of fast magnetic reconnection via subcritical bifurcation We report a phase transition model for the onset of fast magnetic reconnection. By investigating the joint dynamics of streaming instability (i.e., current driven ion acoustic in this paper) and current gradient driven whistler wave prior to the onset of fast reconnection, we show that the nonlinear evolution of current sheet (CS) can be described by a Landau-Ginzburg equation. The phase transition from slow reconnection to fast reconnection occurs at a critical thickness, c ≃ √ 2 v the d e , where v the is π v c electron thermal velocity and v c is the velocity threshold of the st ream ing instability. For current driven ion acoustic, c is ≤ 10d e . If the thickness of the C S is narrower than c , the CS subcritically bifurcates into a rough state, which facilitates breakage of the CS, and consequently initiates fast reconnection.

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Section: Subcritical Bifurcation Of the Cssupporting

confidence: 75%

Onset of fast magnetic reconnection via subcritical bifurcation

Guo

Wang

2015

Front. Phys.

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“…The conservation of generalized magnetic field topology characterized by H e (see (11)) while minimizing H (see (4)) prevents the latter from decaying to zero in an EMHD relaxation process. This may be seen by following along the lines of Arnol'd [18].…”

Section: Appendixmentioning

confidence: 99%

“…The frozen-in condition of magnetic field in EMHD is destroyed by electron inertia. Observations of plasmas in the magnetosphere (Deng and Matsumoto [3]) and laboratory (Ren et al [4]) showed that magnetic reconnection process is initiated in very thin current sheets (thickness ∼ 0 (d e )).…”

Section: Introductionmentioning

confidence: 99%

Plasma relaxation and topological aspects in electron magnetohydrodynamics

Shivamoggi

2016

Physics of Plasmas

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Parker's formulation of isotopological plasma relaxation process toward minimum magnetics energy states in magnetohydrodynamics (MHD) is extended to electron MHD (EMHD). The lower bound on magnetic energy in EMHD is determined by both the magnetic field and the electron vorticity field topologies, and is shown to be reduced further in EMHD by an amount proportional to the sum of total electron-flow kinetic energy and total electron-flow enstrophy. The EMHD Beltrami condition becomes equivalent to the potential vorticity conservation equation in two-dimensional (2D) hydrodynamics, and the torsion coefficient and turns out to be proportional to potential vorticity. The winding pattern of the magnetic field lines appears to evolve therefore in the same way as potential vorticity lines in 2D hydrodynamics.1

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“…Two-dimensional ͑2D͒ kinetic simulations are in excellent agreement with this scaling, with the observed half thickness of the electron layer in the range ␦ e Ϸ͑1-2͒d e . However, somewhat thicker electron layers have been inferred from satellite observations, 15,16 where ␦ e ϳ͑3-5͒d e , and recent measurements 3,17,18 on the Magnetic Reconnection Experi-ment ͑MRX͒, where ␦ e ϳ 8d e . These measurements have important implications for the nature of the dissipation mechanism operative at the X-line.…”

Section: Introductionmentioning

confidence: 99%

“…26 Calculated in-plane electron flows display similar features to numerical simulations with geometry and boundary conditions different from that of the experiment. 27 Recently improved diagnostics have enabled a 2.5ϫ improved resolution, opening up the possibility of detailed comparisons with simulations 3,17,18 to better understand the structure of the electron layer.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional Fully Kinetic Simulations Of Driven Magnetic Reconnection With Boundary Conditions Relevant To The Magnetic Reconnection Experimen

S.¹,

Daughton²,

Roytershteyn³

et al. 2008

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Two-dimensional fully kinetic simulations are performed using global boundary conditions relevant to model the Magnetic Reconnection Experiment ͑MRX͒ ͓M. Yamada et al., Phys Plasmas 4, 1936 ͑1997͔͒. The geometry is scaled in terms of the ion kinetic scales in the experiment, and a reconnection layer is created by reducing the toroidal current in the flux cores in a manner similar to the actual experiment. The ion-scale features in these kinetic simulations are in remarkable agreement with those observed in MRX, including the reconnection inflow rate and quadrupole field structure. In contrast, there are significant discrepancies in the simulated structure of the electron layer that remain unexplained. In particular, the measured thickness of the electron layers is 3-5 times thicker in MRX than in the kinetic simulations. The layer length is highly sensitive to downstream boundary conditions as well as the time over which the simulation is driven. However, for a fixed set of chosen boundary conditions, an extrapolation of the scaling with the ion to electron mass ratio implies that at realistic mass ratio both the length and width will be too small compared to the experiment. This discrepancy implies that the basic electron layer physics may differ significantly between MRX and the two-dimensional, collisionless simulations. The two leading possibilities to explain the discrepancy are weak Coulomb collisions and three-dimensional effects that are present in the experiment but not included in the simulation model.

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Identification of the Electron-Diffusion Region during Magnetic Reconnection in a Laboratory Plasma

Cited by 64 publications

References 30 publications

Onset of fast magnetic reconnection via subcritical bifurcation

Onset of fast magnetic reconnection via subcritical bifurcation

Plasma relaxation and topological aspects in electron magnetohydrodynamics

Two-dimensional Fully Kinetic Simulations Of Driven Magnetic Reconnection With Boundary Conditions Relevant To The Magnetic Reconnection Experimen

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