Formation of self-organized shear structures in thin current sheets

Self‐consistent kinetic (particle‐in‐cell) model of magnetotail thin current sheet (TCS) is used to understand the formation of self‐consistent sheared magnetic structures. It is shown that shear configurations appear in TCS as a result of self‐consistent evolution of some initial magnetic perturbation at the current sheet center. Two general shapes of shear TCS components are found as a function of the transverse coordinate: symmetric and antisymmetric. We show that TCS formation goes together with the emergence of field‐aligned currents in the center of the current sheet, as a result of north‐south asymmetry of quasi‐adiabatic ion motions. Ion drift currents can also contribute to the magnetic shear evolution, but their role is much less significant, their contribution depending upon the normal component Bz and the amplitude of the initial perturbation in TCS. Parametric maps illustrating different types of TCS equilibria are presented that show a higher probability of formation of symmetric shear TCS configuration at lower values of the normal magnetic component. Key Points Thin current sheet model with shear magnetic component is developed Magnetic shear can be formed self‐consistently in current sheets Ion dynamics asymmetry in current sheets is the reason of shear appearance