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E. E. Grigorenko R. Koleva L. M. Zelenyi J. -A. Sauvaud 《Geomagnetism and Aeronomy》2010,50(6):720-732
We present an analysis of two crossings of the plasma sheet boundary layer (PSBL) in Earth’s magnetotail by a quartet of Cluster
satellites, accomplished both in the absolutely quiet geomagnetic interval and in the restoration period between two substorms.
It is found that in the quiet period, field-aligned electric currents were not observed in the PSBL, in spite of presence
in this region of high-velocity ions moving toward Earth along the magnetic field lines at velocities of ∼1400 km/s. This
means that in the given event, ions and electrons moved together; i.e., high-velocity ions were a part of the accelerated
plasma flow. In the disturbed period, the Cluster satellites detected a system of two oppositely directed field-aligned currents,
which can be associated with the presence of the X line rather close to the Earth. Owing to multipoint Cluster observations, we managed to estimate the spatial size of a current
structure (along the normal to the PSBL surface), which was equal, for a current flowing toward Earth along the high-latitude
PSBL boundary, to about 1600 km, which is comparable with the value of the inertial radius of ions. This agrees with the scenario
of spatial separation of charges and formation of the Hall system of currents in the magnetic reconnection region. The duration
of observation of the given current structure was ∼12 min., which points to the quasi-steady-state character of reconnection. 相似文献