A model of the current sheet in the Earth's magnetotail

The thin current sheet of the Earth's magnetotail is the key element of the entire magnetosphere dynamics that significantly depends on a current sheet configuration. Spacecraft measurements have shown that the ion pressure tensor in thin current sheets is essentially isotropic, but widely used two-dimensional current sheet models with isotropic pressure tensor underestimate the current density in the current sheet. In this paper, we develop a set of one-dimensional kinetic models, which demonstrate that although the plasma can be on average isotropic, due to complex kinetic features of the ion distribution function, the current density can be larger than that predicted by isotropic models. These models demonstrate that the current density in thin current sheets crucially depends on the kinetic features of the ion distribution function.