Multi‐point observations of the Hall electromagnetic field and secondary island formation during magnetic reconnection

Eastwood, J. P.; Phan, T. D.; Mozer, F. S.; Shay, M. A.; Fujimoto, M.; Retinò, Alessandro; Hesse, Michael; Balogh, A.; Lucek, E.; Dandouras, I.

doi:10.1029/2006ja012158

Cited by 135 publications

(201 citation statements)

References 54 publications

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“…Since performing in situ measurements for various parameters and the energetic particles in the reconnection region of the solar flare is impossible (at least in the foreseeable future) although performing the similar measurements in the Earth's magnetosphere environment has been done for decades (see Eastwood et al 2007;Retinó et al , 2008; and references therein), conducting alternative laboratory experiments becomes a very viable approach.…”

Section: Outflows Observed During Laser-driven Reconnectionmentioning

confidence: 99%

Review on Current Sheets in CME Development: Theories and Observations

et al. 2015

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We introduce how the catastrophe model for solar eruptions predicted the formation and development of the long current sheet (CS) and how the observations were used to recognize the CS at the place where the CS is presumably located. Then, we discuss the direct measurement of the CS region thickness by studying the brightness distribution of the CS region at different wavelengths. The thickness ranges from 10 4 km to about 10 5 km at heights between 0.27 and 1.16 R from the solar surface. But the traditional theory indicates that the CS is as thin as the proton Larmor radius, which is of order tens of meters in the corona. We look into the huge difference in the thickness between observations and theoretical expectations. The possible impacts that affect measurements and results are studied, and physical causes leading to a thick CS region in which reconnection can still occur at a reasonably fast rate are analyzed. Studies in both theories and observations suggest that the difference between the true value and the apparent value of the CS thickness is not significant as long as the CS could be recognised in observations. We review observations that show complex structures and flows inside the CS region and present recent numerical modelling results on some aspects of these structures. Both observations and numerical experiments indicate that the downward reconnection outflows are usually slower than the upward ones in the same eruptive event. Numerical simulations show that the complex structure inside CS and its temporal behavior as a result of turbulence and the Petschek-type slow-mode shock could probably account for the thick CS and fast reconnection. But whether the CS itself is that thick still remains unknown since, for the time being, we cannot measure the electric current directly in that region. We also review the most recent laboratory experiments of reconnection driven by energetic laser beams, and discuss some important topics for future works.

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Section: Outflows Observed During Laser-driven Reconnectionmentioning

confidence: 99%

Review on Current Sheets in CME Development: Theories and Observations

et al. 2015

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“…Another event is between 09:41 and 09:57 UT on 22 August 2001. This event has been studied by Eastwood et al (2007). They reported the Hall magnetic and electric fields in the ion diffusion region from both hemispheres.…”

Section: Thin Current Sheetmentioning

confidence: 99%

Comparisons of electron acceleration efficiency among different structures during magnetic reconnection: a Cluster multicase study

Zhou

Deng³

et al. 2015

Ann. Geophys.

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Abstract. Magnetic reconnection has long been believed to be an efficient engine for energetic electrons production. Four different structures have been proposed for electrons being energized: flux pileup region, density cavity located around the separatrix, magnetic island and thin current sheet. In this paper, we compare the electron acceleration efficiency among these structures based on 12 magnetotail reconnection events observed by the Cluster spacecraft in [2001][2002][2003][2004][2005][2006]. We used the flux ratio between the energetic electrons (> 50 keV) and lower energy electrons (< 26 keV) to quantify the electron acceleration efficiency. We do not find any specific sequence in which electrons are accelerated within these structures, though the flux pileup region, magnetic island and thin current sheet have higher probabilities to reach the maximum efficiency among the four structures than the density cavity. However, the most efficient electron energization usually occurs outside these structures. We suggest that other structures may also play important roles in energizing electrons. Our results could provide important constraints for the further modeling of electron acceleration during magnetic reconnection.

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“…If a spacecraft mission, such as that discussed in Ref. [12], were to pass through a reconnection region and observe one of these line profiles, it would be possible to distinguish between the possible reconnection setups accordingly.…”

Section: Fig 5: (Left Panels)mentioning

confidence: 99%

The effects of ion mass variation and domain size on octupolar out-of-plane magnetic field generation in collisionless magnetic reconnection

Pahlen

Tsiklauri

2015

Physics of Plasmas

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J. Graf von der Pahlen and D. Tsiklauri, Phys. Plas. 21, 060705 (2014), established that the generation of octupolar out-of-plane magnetic field structure in a stressed X-point collapse is due to ion currents. The field has a central region, comprising of the well-known qaudrupolar field (quadrupolar components), as well as four additional poles of reversed polarity closer to the corners of the domain (octupolar components). In this extended work, the dependence of the octupolar structure on domain size and ion mass variation is investigated. Simulations show that the strength and spatial structure of the generated octupolar magnetic field is independent of ion to electron mass ratio. Thus showing that ion currents play a significant role in out-of-plane magnetic structure generation in physically realistic scenarios. Simulations of different system sizes show that the width of the octupolar structure remains the same and has a spacial extent of the order of the ion inertial length. The width of the structure thus appears to be independent on boundary condition effects. The length of the octupolar structure however increases for greater domain sizes, prescribed by the external system size. This was found to be a consequence of the structure of the in-plane magnetic field in the outflow region halting the particle flow and thus terminating the in-plane currents that generate the out-of-plane field. The generation of octupolar magnetic field structure is also established in a tearing-mode reconnection scenario. The differences in the generation of the octupolar field and resulting qualitative differences between X-point collapse and tearing-mode are discussed.

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Multi‐point observations of the Hall electromagnetic field and secondary island formation during magnetic reconnection

Cited by 135 publications

References 54 publications

Review on Current Sheets in CME Development: Theories and Observations

Review on Current Sheets in CME Development: Theories and Observations

Comparisons of electron acceleration efficiency among different structures during magnetic reconnection: a Cluster multicase study

The effects of ion mass variation and domain size on octupolar out-of-plane magnetic field generation in collisionless magnetic reconnection

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