Fragmentation during merging of plasmoids in the magnetic field reconnection

Karlický, M.; Bárta, M.; Nickeler, D. H.

doi:10.1051/0004-6361/201218781

Cited by 18 publications

(16 citation statements)

References 42 publications

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“…Similar null generation in the outflow regions has recently been described in Ref. 47 in 2D as a result of local enhancements in plasma-b within sheared eddying outflows. We do not investigate these bifurcations further, but postulate that a similar process may be occurring.…”

Section: Outflow Jetssupporting

confidence: 83%

Dynamic topology and flux rope evolution during non-linear tearing of 3D null point current sheets

Wyper

Pontin

2014

Physics of Plasmas

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. In this work, the dynamic magnetic field within a tearing-unstable three-dimensional current sheet about a magnetic null point is described in detail. We focus on the evolution of the magnetic null points and flux ropes that are formed during the tearing process. Generally, we find that both magnetic structures are created prolifically within the layer and are non-trivially related. We examine how nulls are created and annihilated during bifurcation processes, and describe how they evolve within the current layer. The type of null bifurcation first observed is associated with the formation of pairs of flux ropes within the current layer. We also find that new nulls form within these flux ropes, both following internal reconnection and as adjacent flux ropes interact. The flux ropes exhibit a complex evolution, driven by a combination of ideal kinking and their interaction with the outflow jets from the main layer. The finite size of the unstable layer also allows us to consider the wider effects of flux rope generation. We find that the unstable current layer acts as a source of torsional magnetohydrodynamic waves and dynamic braiding of magnetic fields. The implications of these results to several areas of heliophysics are discussed. V C 2014 AIP Publishing LLC.

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Section: Outflow Jetssupporting

confidence: 83%

Dynamic topology and flux rope evolution during non-linear tearing of 3D null point current sheets

Wyper

Pontin

2014

Physics of Plasmas

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“…The possibility of particle acceleration by cascading reconnection was mentioned firstly by Shibata & Tanuma 2001. They conjectured that magnetic islands could be formed at many scales by tearing-mode instabilities of the stretching current sheet. Later this concept are confirmed by theoretical approaches (e.g., Loureiro et al 2007;Uzdensky et al 2010), observations (e.g., Hoshino et al 1994Karlický 2004), AMR MHD simulations (e.g., Bárta et al 2011) and particle in cell (PIC) simulations (e.g., Karlický et al 2012). The electron acceleration by many reconnection sites was studied by Lin 2012 andGordovskyy et al 2010a,b. In their studies, however, they assumed arbitrary ad-hoc prescribed anomalous resistivity models to reveal the accelerating fields.…”

Section: Contrary Tomentioning

confidence: 82%

Electron Acceleration by Cascading Reconnection in the Solar Corona. I. Magnetic Gradient and Curvature Drift Effects

Zhou

Büchner

Bárta

et al. 2015

ApJ

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Aims. We investigate the electron acceleration in convective electric fields of cascading magnetic reconnection in a flaring solar corona and show the resulting hard X-ray (HXR) radiation spectra caused by Bremsstrahlung for the coronal source.Methods. We perform test particle calculation of electron motions in the framework of a guiding center approximation. The electromagnetic fields and their derivatives along electron trajectories are obtained by linearly interpolating the results of high-resolution adaptive mesh refinement (AMR) MHD simulations of cascading magnetic reconnection. Hard X-ray (HXR) spectra are calculated using an optically thin Bremsstrahlung model. Results. Magnetic gradients and curvatures in cascading reconnection current sheet accelerate electrons: trapped in magnetic islands, precipitating to the chromosphere and ejected into the interplanetary space. The final location of an electron is determined by its initial position, pitch angle and velocity. These initial conditions also influence electron acceleration efficiency. Most of electrons have enhanced perpendicular energy. Magnetic curvature and gradient driven acceleration efficiency along the magnetic field increases with the increase of the magnetic field resolution. It was shown that for a sufficiently high resolution of the electromagnetic fields, adaptive mesh refinement (AMR) MHD simulations are needed. Trapped electrons can be accelerated to energies up to half of MeV, precipitating ones to more than 60 keV in the refined smaller-scale magnetic structures. Trapped electrons are considered to cause the observed bright spots along coronal mass ejection CME-trailing current sheets as well as the flare loop-top HXR emissions. Another observable effect is the locations of the precipitating energetic electrons with respect to the polarity inversion line (PIL). A stronger asymmetry of the energetic electron precipita-Article number, page 1 of 27 arXiv:1504.06486v1 [astro-ph.SR] 24 Apr 2015 X. Zhou et al.: Electron acceleration by cascading reconnection in the solar corona tions around the PIL is obtained with sufficiently well resolved smaller-scale magnetic structures than that in the coarsely resolved ones due to the asymmetry in the parallel magnetic curvature acceleration.

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“…One is due to the plasma instabilities and another one is caused by the motions of the plasmoid and plasma flows. Such two types of turbulence have been studied recently on a kinetic scale by Karlický, Bárta & Nickeler (). This result is very important for us to understand how the plasmoid governs the scale, especially the thickness, of the CS.…”

Section: Results Of Numerical Experimentsmentioning

confidence: 99%

Numerical experiments on magnetic reconnection in solar flare and coronal mass ejection current sheets

Mei

et al. 2012

Monthly Notices of the Royal Astronomical Society

100

108

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Magnetic reconnection plays a critical role in energy conversion during solar eruptions. This paper presents a set of magnetohydrodynamic experiments for the magnetic reconnection process in a current sheet (CS) formed in the wake of the rising flux rope. The eruption results from the loss of equilibrium in a magnetic configuration that includes a current-carrying flux rope, representing a pre-existing filament. In order to study the fine structure and micro processes inside the CS, mesh refinement is used to reduce the numerical diffusion. We start with a uniform, explicitly defined resistivity which results in a Lundquist number S = 10 4 in the vicinity of CS. The use of mesh refinement allows the simulation to capture highresolution features such as plasmoids from the tearing mode and plasmoid instability regions of turbulence and slow-mode shocks. Inside the CS, magnetic reconnection goes through the Sweet-Parker and the fractal stages, and eventually displays a time-dependent Petschek pattern. Our results support the concept of fractal reconnection suggested by Shibata et al. and Shibata & Tanuma, and also suggest that the CS evolves through Sweet-Parker reconnection prior to the fast reconnection stage. For the first time, the detailed features and/or fine structures inside the coronal mass ejection/flare CS in the eruption were investigated in this work.

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Fragmentation during merging of plasmoids in the magnetic field reconnection

Cited by 18 publications

References 42 publications

Dynamic topology and flux rope evolution during non-linear tearing of 3D null point current sheets

Dynamic topology and flux rope evolution during non-linear tearing of 3D null point current sheets

Electron Acceleration by Cascading Reconnection in the Solar Corona. I. Magnetic Gradient and Curvature Drift Effects

Numerical experiments on magnetic reconnection in solar flare and coronal mass ejection current sheets

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