Magnetic reconnection with asymmetry in the outflow direction

Murphy, N. A.; Sovinec, C. R.; Cassak, P. A.

doi:10.1029/2009ja015183

Cited by 28 publications

(38 citation statements)

References 113 publications

(166 reference statements)

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“…This is consistent with the predictions of recent reconnection models (e.g. Murphy et al 2010;Reeves et al 2010) with the energy released in the current sheet pumped into the plasmoid.…”

Section: Discussionsupporting

confidence: 91%

Multi-thermal dynamics and energetics of a coronal mass ejection in the low solar atmosphere

Hannah

Kontar

2013

A&A

104

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Aims. The aim of this work is to determine the multi-thermal characteristics and plasma energetics of an eruptive plasmoid and occulted flare observed by the Solar Dynamics Observatory's Atmospheric Imaging Assembly (SDO/AIA). Methods. We study a 2010 Nov. 3 event (peaking at 12:20 UT in GOES soft X-rays) of a coronal mass ejection and occulted flare that demonstrates the morphology of a classic erupting flux rope. The high spatial and time resolution and six coronal channels of the SDO/AIA images allows the dynamics of the multi-thermal emission during the initial phases of eruption to be studied in detail. The differential emission measure is calculated, using an optimized version of a regularized inversion method, for each pixel across the six channels at different times, resulting in emission measure maps and movies in a variety of temperature ranges. Results. We find that the core of the erupting plasmoid is hot (8-11, 11-14 MK) with a similarly hot filamentary "stem" structure connecting it to the lower atmosphere, which could be interpreted as the current sheet in the flux rope model, though is wider than these models suggest. The velocity of the leading edge of the eruption is 597-664 km s −1 in the temperature range ≥3-4 MK and between 1029-1246 km s −1 for ≤2-3 MK. We estimate the density (in 11-14 MK) of the erupting core and stem during the impulsive phase to be about 3 × 10 9 cm −3 , 6 × 10 9 cm −3 , 9 × 10 8 cm −3 in the plasmoid core, stem, and surrounding envelope of material. This gives thermal energy estimates of 5 × 10 29 erg, 1 × 10 29 erg, and 2 × 10 30 erg. The kinetic energy for the core and envelope is slightly lower. The thermal energy of the core and current sheet grows during the eruption, suggesting continuous influx of energy presumably via reconnection. Conclusions. The combination of the optimized regularized inversion method and SDO/AIA data allows the multi-thermal characteristics (i.e. velocity, density, and thermal energies) of the plasmoid eruption to be determined.

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“…This is consistent with the predictions of recent reconnection models (e.g. Murphy et al 2010;Reeves et al 2010) with the energy released in the current sheet pumped into the plasmoid.…”

Section: Discussionsupporting

confidence: 91%

Multi-thermal dynamics and energetics of a coronal mass ejection in the low solar atmosphere

Hannah

Kontar

2013

A&A

104

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“…However, the gap between these experiments and actual major solar eruptions is also apparent. Those by Forbes & Malherbe (), Bárta, Vršnak & Karlický (), Karlický & Bárta (), Bárta et al () and Shen et al () are for the scenario of the Kopp–Pneuman two‐ribbon flare, in which the CME is supposed to be at infinity; those by Loureiro et al (), Huang et al (), Murphy () and Murphy, Sovinec & Cassak () are more likely for the cases occurring in the lab or for the pure theoretical studies; and that by Riley et al () does include both flare and CME, but it does not reveal enough details inside the sheet.…”

Section: Introductionmentioning

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

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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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“…For comparison, the outflow speed v out is plotted as the solid (red) line. Asymmetric outflows occur when there is a pressure gradient in the outflow direction [32], and since such gradients self-consistently generate here, v out is calculated as the average of the maximum electron outflow speeds from either side of the reconnection site, averaged over 5d e when turbulent. Figure 2(b) reveals that v Ãe is small initially, but increases in time once the pressure gradient reaches the reconnection site at t ' 140.…”

mentioning

confidence: 99%

Model for Incomplete Reconnection in Sawtooth Crashes

Beidler

Cassak

2011

Phys. Rev. Lett.

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A model for incomplete reconnection in sawtooth crashes is presented. The reconnection inflow during the crash phase of sawteeth self-consistently convects the high pressure core toward the reconnection site, raising the pressure gradient there. Reconnection shuts off if the diamagnetic drift speed at the reconnection site exceeds a threshold, which may explain incomplete reconnection. The relaxation of magnetic shear after reconnection stops may explain the destabilization of ideal interchange instabilities reported previously. Proof-of-principle two-fluid simulations confirm this basic picture. Predictions of the model compare favorably to data from the Mega Ampere Spherical Tokamak. Applications to transport modeling of sawteeth are discussed. The results should apply across tokamaks, including ITER.

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Magnetic reconnection with asymmetry in the outflow direction

Cited by 28 publications

References 113 publications

Multi-thermal dynamics and energetics of a coronal mass ejection in the low solar atmosphere

Multi-thermal dynamics and energetics of a coronal mass ejection in the low solar atmosphere

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

Model for Incomplete Reconnection in Sawtooth Crashes

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