ИСТИНА

Thin current sheets with a characteristic thickness about one to several proton gyroradii can be observed in planetary magnetospheres during substorms, when a relatively thick magnetotail current sheet is compressed to extremely small thickness and then spontaneously destructed. This process is accompanied by active processes such as plasma acceleration, generation of strong electric fields and magnetohydrodynamic waves. The model of current sheet thinning is developed and investigated, were the presence of protons and heavy oxygen populations is taken into account. The structure of thin current sheets in multicomponent plasma often observed in situ is investigated. It is shown that the relaxation of current sheet to the equilibrium state in two-component plasma can have a complex character. Thus the formation of multiscale embedded current sheet can take place. At some parameters only one plasma component can support the current, while the other one can enter the chaotic regime and does not contribute to the current density. The presence of oxygen ions can lead to the characteristic bifurcation of current density profile, as well as the smoothing of a negative current density at current sheet edges.