The Superthermal Electrons Ionosphere- Magnetosphere Transport and Their Role in the Formation of Ion Outflows

The superthermal electrons (SE) are the major energy contributor to the ionosphere and inner magnetosphere via the Coulomb collision processes. The SE escape from the ionosphere to the plasmasphere is controlled by strong Coulomb coupling with the thermal plasma distribution along the entire magnetic field line. The plasma distribution along the field line, in turn, is controlled by electron and ion temperature distributions that are mostly determined by SE heating of the thermal electrons. The SE also are contribute to the formation of the polar wind and plamaspheric refilling processes. As the plasma flows up and out of the topside ionosphere, the flow conditions change from subsonic to supersonic, from collision-dominated to collisionless, and from O+ dominance to H+ dominance. In the collisionless regime, the ion velocity distributions become highly non-Maxwellian and the coupling between various plasma species occurs through the development of a self-consistent potential. The reason for the formation of a selfconsistent potential in the collisionless plasma is quite clear. High mobility electrons tend to overtake ions. As a result, the electric neutrality of the plasma is violated and an electric field appears which constrains the electrons, forcing them, on average, to travel together with the ions. Sources of free energy that power this ion acceleration process include (but not limited) photoelectron, electron precipitation, field-aligned currents, velocity shears, and Alfvénic Poynting flux. The combine effect of all these processes on ionospheric ion outflows will be investigated in a framework of the kinetic model that has been developed in our previous papers in order to study the polar wind transport in the presence of photoelectrons