Interaction of multiple magnetic islands in a long current sheet: Two‐fluid simulations

Nakamura, Takuma; Fujimoto, M.; Sekiya, Hayato

doi:10.1029/2009gl041858

Cited by 11 publications

(14 citation statements)

References 20 publications

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“…The reconnection rate is greatly reduced only when outflow from both sides of the current sheet is blocked. This helps explain results by Oka et al [2008], who found that the presence of an obstacle on one downstream side of the current sheet does not greatly impact the reconnection rate, and by Nakamura et al [2010], who found that initial X‐lines near the edges of a region of multiple X‐lines tend to win out over X‐lines in the central part of that region.…”

Section: Discussionmentioning

confidence: 64%

“…Reconnection occurring at each of these sites will in general be asymmetric in the inflow and outflow directions, as well as the out‐of‐plane direction. Reconnection processes involving multiple competing reconnection sites or multiple magnetic islands [e.g., Lee and Fu , 1986; Drake et al , 2006; J. Lin et al , 2008; Chen et al , 2009; Nakamura et al , 2010] will also likely involve asymmetry in the outflow direction, especially if the X‐lines are not evenly spaced or develop at different rates.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic reconnection with asymmetry in the outflow direction

2010

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[1] Magnetic reconnection with asymmetry in the outflow direction occurs in the Earth's magnetotail, coronal mass ejections, flux cancellation events, astrophysical disks, spheromak merging experiments, and elsewhere in nature and the laboratory. A control volume analysis is performed for the case of steady antiparallel magnetic reconnection with asymmetric downstream pressure to derive scaling relations for the outflow velocity from each side of the current sheet and the reconnection rate. Simple relationships for outflow velocity are presented for the incompressible case and the case of symmetric downstream pressure but asymmetric downstream density. Asymmetry alone is not found to greatly affect the reconnection rate. The flow stagnation point and magnetic field null do not coincide in a steady state unless the pressure gradient is negligible at the flow stagnation point. The predictions of the model are compared with resistive MHD simulations of driven reconnection with asymmetry in the outflow direction.

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Section: Discussionmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Magnetic reconnection with asymmetry in the outflow direction

2010

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“…Two‐dimensional particle‐in‐cell simulations of reconnection in the presence of a magnetic wall ahead of an outflow demonstrated that the sufficiently piled‐up magnetic field from the wall side causes the X‐line to retreat with a speed that is ∼0.1 times the Alfvén speed V A [ Oka et al , ]. Two‐dimensional two‐fluid simulations demonstrated that a similar X‐line retreating can also be caused by the interaction of X‐lines (multiple reconnection) in the current sheet [ Nakamura et al , ].…”

Section: Introductionmentioning

confidence: 99%

Motion of reconnection region in the Earth's magnetotail

Alexandrova

Nakamura

Semenov

et al. 2015

Geophysical Research Letters

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We obtain the X‐line velocity in the Earth's magnetotail for 24 reconnection events observed by the Cluster spacecraft between 2001 and 2005. The data set consists of 10 single X‐lines and 14 X‐lines from the time intervals of multiple reconnection. Except for two X‐lines from multiple reconnection, all the X‐lines move tailward (radial outward) along the current sheet, which is consistent with the direction of the pressure gradient. The X‐lines also propagate outward from the midnight sector in the dawn‐dusk direction. The X‐line speed in the Earth‐tail direction is comparable and proportional to the reconnection inflow speed and approximately 0.1 of the reconnection outflow speed. These results suggest that both the global pressure distribution and the local reconnection physics may affect the motion of the X‐line.

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“…3.1 Multiple X-line reconnection 3.1.1 Models of multiple X-line reconnection Multiple X-line reconnection or tearing instabilities in the magnetopause have been put forward as one mechanism for FTE generation (Lee and Fu, 1985). This process is essentially time-dependent because an X-line exists in the direction of the outflow jet from another X-line such that the activity of the former X-line can be affected by that of the latter, and vice versa (e.g., Nakamura et al, 2010b). (Note, however, that if the X-line has a relatively short extent, as inferred from FTE observations reported by Fear et al (2010), multiple X-lines and the resultant reconnection jets may exist more or less independently of each other.)…”

Section: Temporal Aspects Of Magnetopause Reconnectionmentioning

confidence: 99%

Structure and Dynamics of the Magnetopause and Its Boundary Layers

Hasegawa¹

2012

Monogr. Environ. Earth Planets

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The magnetopause is the key region in space for the transfer of solar wind mass, momentum, and energy into the magnetosphere. During the last decade, our understanding of the structure and dynamics of Earth's magnetopause and its boundary layers has advanced considerably, thanks largely to the advent of multi-spacecraft missions such as Cluster and THEMIS. Moreover, various types of physics-based techniques have been developed for visualizing two-or threedimensional plasma and field structures from data taken by one or more spacecraft, providing a new approach to the analysis of the spatiotemporal properties of magnetopause processes, such as magnetic reconnection and the Kelvin-Helmholtz instability (KHI). Information on the size, shape, orientation, and evolution of magnetic flux ropes or flow vortices generated by those processes can be extracted from in situ measurements. Observations show that magnetopause reconnection can be globally continuous for both southward and northward interplanetary magnetic field (IMF) conditions, but even under such circumstances, more than one X-line may exist within a certain (low-latitude or high-latitude) portion on the magnetopause and some X-lines may retreat anti-sunward. The potential global effects of such behavior are discussed. An overview is also given of the identification, excitation, evolution, and possible consequences of the magnetopause KHI: there is evidence for nonlinear KHI growth and associated vortex-induced reconnection under northward IMF. Observation-based estimates indicate that reconnection tailward of both polar cusps can be the dominant mechanism for solar wind plasma entry into the dayside magnetosphere under northward IMF. However, the mechanism by which the transferred plasma is transported into the central portion of the magnetotail, and the role of magnetopause processes in this transport, remain unclear. Future prospects of magnetopause and other relevant studies are also discussed.

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Interaction of multiple magnetic islands in a long current sheet: Two‐fluid simulations

Cited by 11 publications

References 20 publications

Magnetic reconnection with asymmetry in the outflow direction

Magnetic reconnection with asymmetry in the outflow direction

Motion of reconnection region in the Earth's magnetotail

Structure and Dynamics of the Magnetopause and Its Boundary Layers

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