NONSTEADY STATE IONOSPHERE PLASMASPHERE COUPLING OF SUPERTHERMAL ELECTRONS

Numerical solutions to the nonsteady state kinetic equation which desc ribes the transport of Superthermal electrons in the ionosphere and pl asmasphere between the magnetically conjugate regions of the ionospher e are presented. The distribution function in time, distance along arb itrary geomagnetic field lines, energy, and pitch angle are among the parameters calculated by the model. This model represents a unified ap proach by self-consistently coupling the interaction of the two hemisp heres and the trapping of superthermal electrons in the plasmasphere. Our calculations take into account the various ionization and excitati on processes and the effect of an inhomogeneous magnetic field (i.e., magnetic mirroring of precipitating electrons and focusing of escaping electrons along magnetic field lines). Omnidirectional flux spectra a nd pitch angle distributions are shown for various L shells and situat ions, and the features are described in detail. Nonsteady state calcul ations predict that a depleted flux tube can take several hours to rea ch steady state levels again. Plasmaspheric transparencies are calcula ted for different conditions of illumination, scattering processes in the conjugate ionospheres, and field-aligned gradients of the thermal plasma density. Plasmaspheric transparency is found to be: a complicat ed function of not only the plasmaspheric thermal plasma but also the ionospheric sources and scattering processes. A phenomenological model is used to describe the energy transmission, reflection, and depositi on in the plasmasphere. By studying the ionosphere arid plasmasphere a s one system rather than two separate ones, substantial corrections ar e introduced in the values of key parameters describing photoelectron fluxes.