Magnetic guide field generation in collisionless current sheets

Baumjohann, W.; Nakamura, R.; Treumann, R. A.

doi:10.5194/angeo-28-789-2010

Cited by 16 publications

(14 citation statements)

References 35 publications

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“…One may ask, for instance in the 22 August 2001 event, why the two flux ropes, 13 min apart, have opposite core field polarities. One possibility is that the seed of the guide field may have changed [e.g., Baumjohann et al, 2010] if the guide field acts as the seed for the core field generation [Karimabadi et al, 1999]. However, we cannot unambiguously determine whether the sign of the guide field changed during the crossings of the two flux ropes.…”

Section: Summary and Discussionmentioning

confidence: 98%

Correlation of core field polarity of magnetotail flux ropes with the IMF B_y: Reconnection guide field dependency

et al. 2014

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The relationship between the core field and the interplanetary magnetic field (IMF) B y has been addressed by spacecraft observations in the magnetotail, but it is not yet fully clear since observations by Slavin et al. (2003) and Borg et al. (2012) show controversial results. In this study, we examine 13 flux ropes from the Cluster observations to show for the first time that the correlation between the core field B core and the IMF B y depends on the guide field B g . For large guide fields (> 20% of the reconnecting field), we show that the B core is found to correlate with the IMF B y . However, for weak guide fields (< 10% of the reconnecting field) we show that the core fields have either a positive or negative polarity, irrespective of the IMF B y . This result indicates that for weak guide field reconnection the core field generation of the magnetotail flux rope is not governed by the external IMF B y . We can explain the previous controversy in terms of the guide field dependency. We also confirm earlier suggestions that for weak guide field reconnection the flux ropes can have a significant core field whose polarity agrees with the ambient quadrupole Hall field. In addition, the Grad-Shafranov reconstruction results suggest that the axis of the flux rope may have been kinked. Our findings are crucial and can help advance theoretical simulations of the core field generation for weak guide reconnection. Discussions of the possible core field generation for weak guide field will be given in terms of 3-D reconnection.

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Section: Summary and Discussionmentioning

confidence: 98%

Correlation of core field polarity of magnetotail flux ropes with the IMF B_y: Reconnection guide field dependency

et al. 2014

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“…This suggests some other internal processes in current sheets could also operate in generating and magnifying the B y component. Some theories about the internal processes have been presented, e.g., the plasma pressure anisotropy related with MHD‐equilibrium [e.g., Cowley , 1979], plasma convection [e.g., Hau and Erickson , 1995; Nakamura et al , 2008], or the plasma instability [e.g., Baumjohann et al , 2010] in current sheets. The validity of these theories needs to be verified carefully in the future study.…”

Section: Discussionmentioning

confidence: 99%

Profile of strong magnetic field B_y component in magnetotail current sheets

Rong¹,

Wan²,

Shen³

et al. 2012

J. Geophys. Res.

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[1] The strong magnetic field B y component (in GSM coordinates) has been increasingly noticed to play an important role in the dynamics of tail current sheet (CS). The distribution profile of strong B y components in the tail CS (i.e., those with guide field), however, is not well known. In the present work, by using the simultaneous multipoint observations of Cluster satellites, the profile of a strong B y component in tail current sheets is explored, through detailed case studies, as well as in a statistical study. It is discovered that around the midnight meridian, the strength of the strong B y component, i.e., |B y |, is basically enhanced at the center of the CS relative to that in the CS boundaries and lobes and forms a north-south symmetric distribution about the center of CS. Generally, however, for strong guide field cases in the non-midnight meridian, the profile of B y strength basically becomes north-south asymmetric, the strength of the B y component in the northern side of the CS is found to be either stronger or weaker than that in the counterpart southern side. By considering the modulation of the tail flaring magnetic field with magnetic local time, we propose an interpretation to account for the variation of the B y -profile, which is supported by the statistical survey. These results offer an observation basis for further studies.

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“…The Weibel instability has been investigated inside the electron-positron Harris sheet, where structures of the out-of-plane magnetic field are fromed. 29,30 Baumjohann et al 31 studied the structures of the out-of-plane magnetic field inside the electron inertial region in the electron-proton current sheet. They found that the inflow of electrons into the sheet from its two sides may well be capable of selfconsistently generating a weak magnetic guide field via the Weibel instability.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Weibel instability and structures of magnetic island in anti-parallel collisionless magnetic reconnection

Shao

et al. 2011

Physics of Plasmas

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Two-dimensional (2D) particle-in-cell simulations are performed to investigate the structures of the out-of-plane magnetic field in magnetic island, which is produced during anti-parallel collisionless magnetic reconnection. Regular structures with alternate positive and negative values of the out-of-plane magnetic field along the x direction are formed in magnetic island. The generation mechanism of such structures is also proposed in this paper, which is due to the Weibel instability excited by the temperature anisotropy in magnetic island. V

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Magnetic guide field generation in collisionless current sheets

Cited by 16 publications

References 35 publications

Correlation of core field polarity of magnetotail flux ropes with the IMF B_y: Reconnection guide field dependency

Correlation of core field polarity of magnetotail flux ropes with the IMF B_y: Reconnection guide field dependency

Profile of strong magnetic field B_y component in magnetotail current sheets

Weibel instability and structures of magnetic island in anti-parallel collisionless magnetic reconnection

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Magnetic guide field generation in collisionless current sheets

Cited by 16 publications

References 35 publications

Correlation of core field polarity of magnetotail flux ropes with the IMF By: Reconnection guide field dependency

Correlation of core field polarity of magnetotail flux ropes with the IMF By: Reconnection guide field dependency

Profile of strong magnetic field By component in magnetotail current sheets

Weibel instability and structures of magnetic island in anti-parallel collisionless magnetic reconnection

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Correlation of core field polarity of magnetotail flux ropes with the IMF B_y: Reconnection guide field dependency

Correlation of core field polarity of magnetotail flux ropes with the IMF B_y: Reconnection guide field dependency

Profile of strong magnetic field B_y component in magnetotail current sheets