The Alfvén edge in asymmetric reconnection

Vaivads, A.; Khotyaintsev, Yuri; André, Mats

doi:10.5194/angeo-28-1327-2010

Cited by 11 publications

(14 citation statements)

References 12 publications

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“…Here ions with energies from tens to hundreds eV have gyroradii of ∼20 to ∼70 km, and can drift within a layer a few hundred km wide. The same event has been studied by Vaivads et al [2010] where it has been suggested that the region of strong electric fields is an Alfvén edge from the reconnection site. We conclude that − v × B ‐drifting rather cold plasma in the separatrix region can balance the normal electric field.…”

Section: Observations and Interpretationmentioning

confidence: 99%

Magnetic reconnection and cold plasma at the magnetopause

André

Vaivads

Khotyaintsev

et al. 2010

Geophysical Research Letters

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[1] We report on detailed observations by the four Cluster spacecraft of magnetic reconnection and a Flux Transfer Event (FTE) at the magnetopause. We detect cold (eV) plasma at the magnetopause with two independent methods. We show that the cold ions can be essential for the electric field normal to the current sheet in the separatrix region at the edge of the FTE and for the associated acceleration of ions from the magnetosphere into the reconnection jet. The cold ions have small enough gyroradii to drift inside the limited separatrix region and the normal electric field can be balanced by this drift, E ≈ −v × B. The separatrix region also includes cold accelerated electrons, as part of the reconnection current circuit. Citation: André, M., A. Vaivads,

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Section: Observations and Interpretationmentioning

confidence: 99%

Magnetic reconnection and cold plasma at the magnetopause

André

Vaivads

Khotyaintsev

et al. 2010

Geophysical Research Letters

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“…The separatrix and the flow boundary have been identified by using flow, particles, and wave data [ Retinò et al , ; Gosling et al , ; Vaivads et al , ; Retinò et al , ; Matsumoto et al , ; Cattell et al , ; Deng and Matsumoto , ]. Both wave and particles data have been used to identify the separatrix.…”

Section: Cluster Observations and Interpretationmentioning

confidence: 99%

“…Retinò et al [] have also identified the magnetic separatrix by taking a sharp boundary in electric field waveforms using the Wideband Plasma Wave Investigation. Lindstedt et al [] and Vaivads et al [] defined the electron edge or separatrix on the magnetospheric side where the first magnetosheath electrons or parallel electrons with a typical energy of hundreds of eV are observed. The flow boundary has been defined by the density gradient, first observed magnetosheath ions on the magnetospheric side, a sharp change in the ion distribution, the plasma flow V L component increases [ Lindstedt et al , ; Gosling et al , ], and the thermal speed of plasmas [ Vaivads et al , ] by using the flow and particles data.…”

Section: Cluster Observations and Interpretationmentioning

confidence: 99%

“…There are three ways to identify the flow boundary (gray dashed lines), the density gradients (Figure h) [ Vaivads et al , ; Lindstedt et al , ], the velocity changes (Figure i) [ Lindstedt et al , ; Gosling et al , ], and the ion energy spectrum (Figure a) [ Lindstedt et al , ]. We used all three ways to identify the flow boundary on the magnetospheric side, which was observed at 19:02:31 ± 2 s UT and at 19:08:00 ± 2 s UT.…”

Section: Cluster Observations and Interpretationmentioning

confidence: 99%

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Plasma and energetic particle behaviors during asymmetric magnetic reconnection at the magnetopause

et al. 2014

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The factors controlling asymmetric reconnection and the role of the cold plasma population in the reconnection process are two outstanding questions. We present a case study of multipoint Cluster observations demonstrating that the separatrix and flow boundary angles are greater on the magnetosheath than on the magnetospheric side of the magnetopause, probably due to the stronger density than magnetic field asymmetry at this boundary. The motion of cold plasmaspheric ions entering the reconnection region differs from that of warmer magnetosheath and magnetospheric ions. In contrast to the warmer ions, which are probably accelerated by reconnection in the diffusion region near the subsolar magnetopause, the colder ions are simply entrained by × drifts at high latitudes on the recently reconnected magnetic field lines. This indicates that plasmaspheric ions can sometimes play only a very limited role in asymmetric reconnection, in contrast to previous simulation studies. Three cold ion populations (probably H + , He + , and O + ) appear in the energy spectrum, consistent with ion acceleration to a common velocity.

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“…Figure 4ishows that between P and Q the parallel‐to‐antiparallel anisotropy was close to unity at all energies, which might be the region between the separatrix and the electron edge. The electron edge is not well identified in the spectrum data with 3 s resolution, which is due to the large velocity of electrons leading the electron edge located very close to the separatrix [ Vaivads et al , 2010]. At Q, the electrons showed a sharp boundary in the anisotropy data (see Figure 4i) and the electric field reached its maximum of about 1.35 mV/m at the frequency band around 10 Hz in the E spectrum, indicating that the spacecraft crossed the Alfvén wave (or “rotational discontinuity, RD) which is formed on the both side of the current sheet when there is a large difference in the Alfvén speed V A in the fluid description [ Nakamura and Scholer , 2000], and is launched from the reconnection site and stands in the inflow on the lower density (magnetosphere) side of the boundary (RD sp ) [ Lockwood , 1997].…”

Section: Observations and Resultsmentioning

confidence: 99%

Inner plasma structure of the low‐latitude reconnection layer

et al. 2012

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[1] We report a clear transition through a reconnection layer at the low-latitude magnetopause which shows a complete traversal across all reconnected field lines during northwestward interplanetary magnetic field (IMF) conditions. The associated plasma populations confirm details of the electron and ion mixing and the time history and acceleration through the current layer. This case has low magnetic shear with a strong guide field and the reconnection layer contains a single density depletion layer on the magnetosheath side which we suggest results from nearly field-aligned magnetosheath flows. Within the reconnection boundary layer, there are two plasma boundaries, close to the inferred separatrices on the magnetosphere and magnetosheath sides (S sp and S sh ) and two boundaries associated with the Alfvén waves (or Rotational Discontinuities, RD sp and RD sh ). The data are consistent with these being launched from the reconnection site and the plasma distributions are well ordered and suggestive of the time elapsed since reconnection of the field lines observed. In each sub-layer between the boundaries the plasma distribution is different and is centered around the current sheet, responsible for magnetosheath acceleration. We show evidence for a velocity dispersion effect in the electron anisotropy that is consistent with the time elapsed since reconnection. In addition, new evidence is presented for the occurrence of partial reflection of magnetosheath electrons at the magnetopause current layer.

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The Alfvén edge in asymmetric reconnection

Cited by 11 publications

References 12 publications

Magnetic reconnection and cold plasma at the magnetopause

Magnetic reconnection and cold plasma at the magnetopause

Plasma and energetic particle behaviors during asymmetric magnetic reconnection at the magnetopause

Inner plasma structure of the low‐latitude reconnection layer

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