ИСТИНА

Electron and ion distribution functions in the magnetosphere of the Earth in many cases can be described by kappa distributions. Such distributions have a Maxwellian core and a power law spectrum at high energies. Kappa distributions are formed due to relaxation of nonequilibrium distribution functions to the Maxwellian distributions in the conditions of collisionless magnetospheric plasma. Analysis of parameters of kappa distribution is very interesting for the solution of such problems as plasma heating and particle acceleration. Examples of approximations of observed ion distribution functions by kappa distributions during magnetically quite conditions and bi-kappa distributions in the case when plasma populations from two sources are mixed are obtained. Changes of kappa parameters along the trajectories of the flights of THEMIS mission satellites are analyzed. It is shown, that the analysis of the parameters of kappa approximations is the effective method of the magnetospheric dynamics study.