Cluster electric current density measurements within a magnetic flux rope in the plasma sheet

Slavin, J. A.; Lepping, R. P.; Gjerloev, J. W.; Goldstein, M. L.; Fairfield, D. H.; Acuña, M. H.; Balogh, A.; Dunlop, M. W.; Kivelson, M. G.; Khurana, K. K.; Fazakerley, A. N.; Owen, C. J.; Rème, H.; Bosqued, J. M.

doi:10.1029/2002gl016411

Cited by 86 publications

(139 citation statements)

References 21 publications

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“…In a previous study by Slavin et al (2003a), it was demonstrated that the magnetic field measurements of the flux ropes in the near tail can be successfully fitted with force-free flux rope models, thus suggesting that the observed flux ropes propagating towards the Earth are truly force free. This suggestion was further supported by the application of the curlometer technique to a flux rope registered by the Cluster spacecraft in the magnetotail (Slavin et al, 2003b). The analysis showed that the current in the observed flux rope is largely field aligned and although the flux ropes in the magnetotail are not strictly force free the usage of the force-free approximation proves to be reasonable.…”

Section: Analysis and Resultsmentioning

confidence: 75%

Dipolarization fronts in the near-Earth space and substorm dynamics

et al. 2015

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Abstract. During magnetospheric substorms and plasma transport in the Earth's magnetotail various magnetic structures can be detected. Dipolarization fronts and flux ropes are the most prominent structures characteristic for substorm dynamics. However, they are treated as separate magnetotail features independent of each other. In this paper, we analyze a number of dipolarization fronts observed by the THEMIS (Time History of Events and Macroscale Interactions during Substorms) spacecraft at different geocentric distances by applying the magnetohydrostatic Grad-Shafranov (GS) reconstruction technique. Our analysis shows that there is a possibility of dipolarization fronts to originate from highly dissipated flux ropes which are in the late stage of their evolution, subjected to a continuous magnetic deterioration due to the reconnection process. These results may improve our understanding of magnetoplasma processes in Earth's magnetotail.

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Section: Analysis and Resultsmentioning

confidence: 75%

Dipolarization fronts in the near-Earth space and substorm dynamics

et al. 2015

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“…Earthward moving flux ropes have also been observed by Cluster (e.g. Slavin et al, 2003b;Henderson et al, 2006), which implies that multiple X-lines may exist in the tail within 20 R E of the Earth.…”

Section: Introductionmentioning

confidence: 88%

Near-simultaneous magnetotail flux rope observations with Cluster and Double Star

Walsh

Fazakerley²,

Wilson³

et al. 2007

Ann. Geophys.

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Abstract. We present observations of three magnetic flux ropes in the tail of the Earth's magnetosphere on 7 August 2004 by the Cluster and Double Star TC-1 spacecraft. The first two flux rope signatures were observed, nearsimultaneously, by Cluster and TC-1, which were located at (-16.3, -8.7, 0.10) R E GSM and (-10.3, -7.11, 0.81) R E GSM, respectively, a separation of 6.3 R E . A third signature was observed some four minutes later by two of the four Cluster spacecraft, while the other two spacecraft observed a feature resembling a Travelling Compression Region (TCR). These observations are interpreted as three individual flux ropes existing in the magnetotail, the first two, at least, simultaneously. The formation mechanism of the flux ropes and the consequences of their presence for the structure of the magnetotail on this day are discussed in the context of multiple X-point reconnection.

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“…One flux rope event on 22 August 2001 has been verified by Slavin et al [2003aSlavin et al [ , 2003b, who found that it is earthward moving and its size is about 1 R E . Figure 5 demonstrates the magnetic rotation features of this flux rope event as calculated by MRA method.…”

Section: Applicationsmentioning

confidence: 99%

Magnetic field rotation analysis and the applications

et al. 2007

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[1] An analysis technique, termed MRA (magnetic rotation analysis), has been designed to probe three-dimensional magnetic field topology. It is based on estimating the gradient tensor of four-point measurements of the magnetic field which have been taken by the Cluster mission. The method first constructs the symmetrical magnetic rotation tensor and in general terms deduces the rotation rate of magnetic field along one arbitrary direction. In particular, the maximum, medium, and minimum magnetic rotation rates along corresponding characteristic directions of a magnetic structure can be obtained. The value of the curvature of a magnetic field line, for example, is given by the magnetic rotation rate along the magnetic unit vector and its corresponding radius of curvature is readily obtained. MRA has been applied here to analyze the geometrical structure of two distinct magnetospheric structures, i.e., the tail current sheet and the tail flux rope. The normal of the current sheet is the direction at which the magnetic field has the largest rotation rate. The half thickness of the one-dimensional neutral sheet can also be determined from the reciprocal of the maximum magnetic rotation rate. The advantage of the MRA method is that not only it can determine the orientation but also the internal geometrical configuration and spatial scale of the magnetic structures. A key feature of the MRA method is that it provides the detailed picture of the magnetic rotation point by point through any crossing of the current sheet. As a result, the thickness of the neutral sheet (NS) can be explicitly demonstrated to vary with time, as indicated in one case study, where the NS becomes thicker after the onset of a substorm. MRA has also been applied here to analyze the detailed features of magnetic field variations inside of a flux rope. The principal axis of the flux rope is the direction at which the magnetic field rotates at the least rate. The magnetic scale of the flux rope can also be determined (about 1R E in the case chosen). It is also found that there are both frontside-backside and dawn-dusk asymmetries for the flux rope under study.

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Cluster electric current density measurements within a magnetic flux rope in the plasma sheet

Cited by 86 publications

References 21 publications

Dipolarization fronts in the near-Earth space and substorm dynamics

Dipolarization fronts in the near-Earth space and substorm dynamics

Near-simultaneous magnetotail flux rope observations with Cluster and Double Star

Magnetic field rotation analysis and the applications

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