Abstract

Theory of the plasma sheet with medium-scale developed turbulence gives the possibility to explain the main processes of plasma sheet bifurcation and theta-aurora formation during IMF Bz > 0. The model suggests that during IMF Bz > 0 small bulge structure in the plasma sheet center is formed. The polarization of the bulge due to dawnward electron motion and duskward ion motion decreases the large-scale electric field in the bulge region. The decrease of the large-scale field in the conditions of constant coefficient of diffusion leads to the bulge growth. The results of plasma sheet bifurcation and theta-aurora formation modelling are presented.