Structure of the near-Earth plasma sheet during tailward flows

Abstract

A detailed analysis of successive tailward flow bursts in the near-Earth magnetotail (X∼−19 R E) plasma sheet is performed on the basis of in-situ multi-point observations by the Cluster spacecraft on 15 September 2001. The tailward flows were detected during a northward IMF interval, 2.5 h after a substorm expansion. Each flow burst (Vx<300 km/s) was associated with local auroral activation. Enhancements of the parallel and anti-parallel ∼1 keV electron flux were detected during the flows. The spacecraft configuration enables to monitor the neutral sheet (Bx≈0) and the level of B x≈10–15 nT simultaneously, giving a possibility to distinguish between closed plasmoid-like structures and open NFTE-like surges. The data analysis shows NFTE-like structures and localized current filaments embedded into the tailward plasma flow. 3-D shapes of the structures were reconstructed using the four-point magnetic filed measurements and the particle data.