ELECTRON AND ION THERMAL STRUCTURES ABOVE 1000 KM - A MULTIION GENERALIZED TRANSPORT MODEL FOR SUBSONIC FLOWS

A multispecies (electrons, H+, He+, O+) generalized transport model ha s been developed that is based on 16-moment transport theory. This mod el provides a simultaneous and self-consistent solution for the densit ies, drift velocities, parallel and perpendicular temperatures, and pa rallel and perpendicular heat flows of the electrons and each of the t hree ion species. Solutions have been obtained for a wide range of ion ospheric boundary conditions, but this study concentrates on the relat ions between temperature gradients applied at a lower boundary (1000 k m) and the total temperatures and temperature anisotropies that exist at higher altitudes, for electrons, H+ ions, and He+ ions. It is seen that applying even a modest temperature gradient for a particular spec ies has a major effect on the thermal structure of that species at hig her altitudes. Further, while the thermal structures of the various sp ecies are coupled due to Coulomb collisions, this coupling is far more significant for certain pairs of species than for others. For a parti cular species, the presence of a large temperature gradient at the low er boundary may or may not result in highly non-Maxwellian distributio n functions at higher altitudes, depending on the relative magnitudes of the species temperatures and heat flows at those altitudes. Also, i n comparing the total electron heat flows predicted by 16-moment trans port theory with those predicted by the standard, collision-dominated transport theory, close agreement is found. For the ions, however, the differences between the 16-moment and standard models can be very lar ge, depending on the boundary conditions.