Asymmetry in the current sheet and secondary magnetic flux ropes during guide field magnetic reconnection

Rongsheng Wang, Rumi Nakamura, Quanming Lu, Aimin Du, Tielong Zhang, Wolfgang Baumjohann, Yuri V. Khotyaintsev, Martin Volwerk, Mats André, M. Fujimoto, T. K M Nakamura, Andrew N. Fazakerley, Jian Du, Teh Wai Leong, Evgeny V. Panov, Bertalan Zieger, Yongxin Pan, San Lu

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

[1] A magnetic reconnection event with a moderate guide field encountered by Cluster in the near-Earth tail on 28 August 2002 is reported. The guide field points dawnward during this event. The quadrupolar structure of the Hall magnetic field within the ion diffusion region is distorted toward the northern hemisphere in the earthward part while toward the southern hemisphere tailward part of X-line. Observations of current density and electron pitch angle distribution indicate that the distorted quadrupolar structure is formed due to a deformed Hall electron current system. Cluster crossed the ion diffusion region from south to north earthward of the X-line. An electron density cavity is confirmed in the northern separatrix layer while a thin current layer (TCL) is measured in the southern separatrix layer. The TCL is formed due to electrons injected into the X-line along the magnetic field. These observations are different from simulation results where the cavity is produced associated with inflow electrons along the southern separatrix while the strong current sheet appears with the outflow electron beam along the northern separatrix. The energy of the inflowing electron in the separatrix layer could extend up to 10 keV. Energetic electron fluxes up to 50 keV have a clear peak in the TCL. The length of the separatrix layer is estimated to be at least 65 c/wpi. These observations suggest that electrons could be pre-accelerated before they are ejected into the X-line region along the separatrix. Multiple secondary flux ropes moving earthward are observed within the diffusion region. These secondary flux ropes are all identified earthward of the observed TCL. These observations further suggest there are numerous small scale structures within the ion diffusion region.

Original languageEnglish
Article numberA07223
JournalJournal of Geophysical Research: Space Physics
Volume117
Issue number7
DOIs
Publication statusPublished - 2012
Externally publishedYes

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magnetic field reconnection
ropes
current sheets
Magnetic flux
magnetic fields
magnetic flux
asymmetry
electrons
Magnetic fields
magnetic field
electron
Electrons
Ions
Fluxes
ions
ion
cavity
cavities
electron flux
pitch (inclination)

ASJC Scopus subject areas

  • Space and Planetary Science
  • Geophysics

Cite this

Asymmetry in the current sheet and secondary magnetic flux ropes during guide field magnetic reconnection. / Wang, Rongsheng; Nakamura, Rumi; Lu, Quanming; Du, Aimin; Zhang, Tielong; Baumjohann, Wolfgang; Khotyaintsev, Yuri V.; Volwerk, Martin; André, Mats; Fujimoto, M.; Nakamura, T. K M; Fazakerley, Andrew N.; Du, Jian; Wai Leong, Teh; Panov, Evgeny V.; Zieger, Bertalan; Pan, Yongxin; Lu, San.

In: Journal of Geophysical Research: Space Physics, Vol. 117, No. 7, A07223, 2012.

Research output: Contribution to journalArticle

Wang, R, Nakamura, R, Lu, Q, Du, A, Zhang, T, Baumjohann, W, Khotyaintsev, YV, Volwerk, M, André, M, Fujimoto, M, Nakamura, TKM, Fazakerley, AN, Du, J, Wai Leong, T, Panov, EV, Zieger, B, Pan, Y & Lu, S 2012, 'Asymmetry in the current sheet and secondary magnetic flux ropes during guide field magnetic reconnection', Journal of Geophysical Research: Space Physics, vol. 117, no. 7, A07223. https://doi.org/10.1029/2011JA017384
Wang, Rongsheng ; Nakamura, Rumi ; Lu, Quanming ; Du, Aimin ; Zhang, Tielong ; Baumjohann, Wolfgang ; Khotyaintsev, Yuri V. ; Volwerk, Martin ; André, Mats ; Fujimoto, M. ; Nakamura, T. K M ; Fazakerley, Andrew N. ; Du, Jian ; Wai Leong, Teh ; Panov, Evgeny V. ; Zieger, Bertalan ; Pan, Yongxin ; Lu, San. / Asymmetry in the current sheet and secondary magnetic flux ropes during guide field magnetic reconnection. In: Journal of Geophysical Research: Space Physics. 2012 ; Vol. 117, No. 7.
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AU - Wang, Rongsheng

AU - Nakamura, Rumi

AU - Lu, Quanming

AU - Du, Aimin

AU - Zhang, Tielong

AU - Baumjohann, Wolfgang

AU - Khotyaintsev, Yuri V.

AU - Volwerk, Martin

AU - André, Mats

AU - Fujimoto, M.

AU - Nakamura, T. K M

AU - Fazakerley, Andrew N.

AU - Du, Jian

AU - Wai Leong, Teh

AU - Panov, Evgeny V.

AU - Zieger, Bertalan

AU - Pan, Yongxin

AU - Lu, San

PY - 2012

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N2 - [1] A magnetic reconnection event with a moderate guide field encountered by Cluster in the near-Earth tail on 28 August 2002 is reported. The guide field points dawnward during this event. The quadrupolar structure of the Hall magnetic field within the ion diffusion region is distorted toward the northern hemisphere in the earthward part while toward the southern hemisphere tailward part of X-line. Observations of current density and electron pitch angle distribution indicate that the distorted quadrupolar structure is formed due to a deformed Hall electron current system. Cluster crossed the ion diffusion region from south to north earthward of the X-line. An electron density cavity is confirmed in the northern separatrix layer while a thin current layer (TCL) is measured in the southern separatrix layer. The TCL is formed due to electrons injected into the X-line along the magnetic field. These observations are different from simulation results where the cavity is produced associated with inflow electrons along the southern separatrix while the strong current sheet appears with the outflow electron beam along the northern separatrix. The energy of the inflowing electron in the separatrix layer could extend up to 10 keV. Energetic electron fluxes up to 50 keV have a clear peak in the TCL. The length of the separatrix layer is estimated to be at least 65 c/wpi. These observations suggest that electrons could be pre-accelerated before they are ejected into the X-line region along the separatrix. Multiple secondary flux ropes moving earthward are observed within the diffusion region. These secondary flux ropes are all identified earthward of the observed TCL. These observations further suggest there are numerous small scale structures within the ion diffusion region.

AB - [1] A magnetic reconnection event with a moderate guide field encountered by Cluster in the near-Earth tail on 28 August 2002 is reported. The guide field points dawnward during this event. The quadrupolar structure of the Hall magnetic field within the ion diffusion region is distorted toward the northern hemisphere in the earthward part while toward the southern hemisphere tailward part of X-line. Observations of current density and electron pitch angle distribution indicate that the distorted quadrupolar structure is formed due to a deformed Hall electron current system. Cluster crossed the ion diffusion region from south to north earthward of the X-line. An electron density cavity is confirmed in the northern separatrix layer while a thin current layer (TCL) is measured in the southern separatrix layer. The TCL is formed due to electrons injected into the X-line along the magnetic field. These observations are different from simulation results where the cavity is produced associated with inflow electrons along the southern separatrix while the strong current sheet appears with the outflow electron beam along the northern separatrix. The energy of the inflowing electron in the separatrix layer could extend up to 10 keV. Energetic electron fluxes up to 50 keV have a clear peak in the TCL. The length of the separatrix layer is estimated to be at least 65 c/wpi. These observations suggest that electrons could be pre-accelerated before they are ejected into the X-line region along the separatrix. Multiple secondary flux ropes moving earthward are observed within the diffusion region. These secondary flux ropes are all identified earthward of the observed TCL. These observations further suggest there are numerous small scale structures within the ion diffusion region.

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