Experimental Verification of the Hall Effect during Magnetic Reconnection in a Laboratory Plasma

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

doi:10.1103/physrevlett.95.055003

Cited by 194 publications

(167 citation statements)

References 18 publications

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“…7). Both these results confirm an importance of the non-MHD effects in the magnetic field reconnection as presented in the papers by Ji et al (2004) and Ren et al (2005).…”

Section: Discussionsupporting

confidence: 77%

“…Because in our study we use the PIC simulation we decided to check the findings made by Ji et al (2004) and Ren et al (2005) saying that in the collisionless regime of the magnetic field reconnection there are important non-MHD effects. Therefore, in agreement with these papers, we checked a structure of the magnetic field in reconnecting current sheets.…”

Section: Discussionmentioning

confidence: 99%

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Fragmentation during merging of plasmoids in the magnetic field reconnection

Karlický

Bárta

Nickeler

2012

A&A

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Context. Application of the magnetic-reconnection theory onto large-scale events, such as solar flares, requires formation of very thin (kinetic-scale) current sheets within the rather thick flare current layer. Hence, some fragmentation/filamentation mechanisms has to be in action. Aims. We aim at identifying fragmentation mechanisms for magnetic field and current density structures. Namely, we focus at detailed study of the processes during the merging of plasmoids that had been formed in the current layer. Methods. A 2.5-D electromagnetic particle-in-cell model is used and its results analysed. Results. It is shown that the merging process of plasmoids is not a simple process as presented in some previous studies. On the contrary, this process leads to a complex fragmentation. We found two types of fragmentation processes: a) fragmentation in the current sheet generated between the merging plasmoids and b) fragmentation at the boundary of plasma outflow from the reconnection between these plasmoids. While the first type of fragmentation is generated by the tearing-mode (plasmoid) instability of the secondary current sheet, the second one looks to be connected with an increase of the plasma β parameter during these processes. Thus, sheared high-β plasma flows produce this additional fragmentation. Conclusions. The fragmentation and energy transport from large to small scales in a large-scale magnetic reconnection seem to be the result of interplay and positive feedback between instabilities driven by high gradients in both magnetic (intense current density) and velocity (high vorticity) fields.

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“…7). Both these results confirm an importance of the non-MHD effects in the magnetic field reconnection as presented in the papers by Ji et al (2004) and Ren et al (2005).…”

Section: Discussionsupporting

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Fragmentation during merging of plasmoids in the magnetic field reconnection

Karlický

Bárta

Nickeler

2012

A&A

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“…Scale separation between ions and electrons in the form of the quadrupole field associated with Hall reconnection has been observed and characterized. 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: Introductionsupporting

confidence: 54%

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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“…Consistent with this scenario, flux emergence (Longcope et al 2005) and coronal eruption (Liu et al 2009) observations display slow energy release before fast. Transitions at kinetic scales are observed in experiments (Ren et al 2005;Egedal et al 2007). Stellar flare data imply kinetic effects are relevant (Cassak et al 2008).…”

Section: Introductionmentioning

confidence: 66%

The Impact of Microscopic Magnetic Reconnection on Pre-Flare Energy Storage

Cassak

Drake

2009

ApJ

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It is widely accepted that magnetic reconnection releases a large amount of energy during solar flares. Studies of reconnection usually assume that the length scale over which the global (macroscopic) magnetic field reverses is identical to the thickness of the reconnection site. However, in spatially extended high-Lundquist number plasmas such as the solar corona, this scenario is untenable; the reconnection site is microscopic and embedded inside the macroscopic current set up by global fields. We use numerical simulations and scaling arguments to show that embedded effects on reconnection could have a profound influence on energy storage before a flare. From largescale high-Lundquist number resistive magnetohydrodynamics simulations of reconnection with a diffusion region on a much smaller scale than the macroscopic current sheet, we find that the generation of secondary islands is governed by the local magnetic field immediately upstream of the diffusion region rather than the (potentially much larger) global field. This diminishes the production of secondary islands and leads to a thicker diffusion region than those predicted using the global field strength. Such considerations are crucial for understanding the onset of solar eruptions and how energy accumulates before such eruptions. We argue that if reconnection with secondary islands is fast, the energy storage times before an eruption are too small to explain observations. If reconnection with secondary islands remains slow, embedded effects cause the diffusion region to begin far wider than kinetic scales, so energy storage before a flare can occur while collisional (Sweet-Parker) reconnection with secondary islands proceeds.

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Experimental Verification of the Hall Effect during Magnetic Reconnection in a Laboratory Plasma

Cited by 194 publications

References 18 publications

Fragmentation during merging of plasmoids in the magnetic field reconnection

Fragmentation during merging of plasmoids in the magnetic field reconnection

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

The Impact of Microscopic Magnetic Reconnection on Pre-Flare Energy Storage

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