Kinetic Structure of Current Sheets in the Earth Magnetotail

Abstract

In this paper we present a short review of kinetic models of the thin current sheet and corresponding Cluster observations in the Earth magnetotail. We concentrate mainly on manifestations of non-fluid ion kinetic effects. We discuss the different approaches to model description of the proton component and show that current sheets observed by Cluster contain population of particles with transient trajectories, which, in fact, are main carriers of the transverse current in the Earth magnetotail. We describe the influence of the electron temperature anisotropy on the current sheet structure. We demonstrate that the decoupling of proton and electron motions in thin current sheets results in appearance of the earthward electrostatic field, which redistributes currents due to the cross-field drift. This effect can describe small or negative proton currents often observed by Cluster.