Nonlinear kinetic modeling of early stage plasmaspheric refilling

Abstract

A new time‐dependent kinetic model is used to investigate the effects of self‐consistency and hot plasma influences on plasmaspheric refilling. The model employs a direct solution of the kinetic equation with a Fokker‐Planck Coulomb collision operator to obtain the phase space distribution function of the thermal protons along a field line. Of particular interest is the influence of several processes on the source cone distribution function formation. It is found that a self‐consistent ion temperature in the collision term can increase or decrease the equatorial plane density, depending not only on the choice of ion temperature in the static‐background calculations but also on the form of the nonlinear representation. The inclusion of a self‐consistent polarization electric field increases the early stage equatorial plane density by a factor of 2. Investigations of the effects of anisotropic hot plasma populations on the refilling rates shows that, after a slight initial decrease in equatorial density from clearing out the initial distribution, there is a 10 to 30% increase after 4 hours due to these populations. This increase is due primarily to a slowing of the refilling streams near the equator from the reversed electric field.