Medium-scale splitting of outflowing field-aligned currents and kappa distribution of magnetospheric ions

The medium-scale (50–200 km in the projection onto ionospheric altitudes) splitting of the field-aligned currents flowing out of the ionosphere has been considered in the case when the approximation of the distribution function of hot magnetospheric ions by the kappa distribution is taken into account. It was assumed that the condition of magnetostatic equilibrium and isotropy of hot magnetospheric plasma pressure is satisfied in the magnetosphere. The theoretical parameter of magnetospheric plasma hot stratification has been obtained for the case of ion kappa distribution. The parameter characterizes the number of structures into which the band of the field-aligned current flowing out of the ionosphere is split. The theoretical predictions have been compared with the observations on the Intercosmos-Bulgaria-1300 and Aureol-3 satellites. It has been indicated that the number of measured structures is in better agreement with that of the theoretically predicted structures in 70% of cases if the non-Maxwellian tails of ion distribution functions are taken into account.