Asymptotic behaviour of a kinetic solar wind model

In this Solar Wind Model, the Coulomb collisions, with impact parameter smaller than the Debye length, have been neglected beyond the baropause located at 6.6 Solar radii. The radial distribution of the electric potential is calculated in order to satisfy the local and global quasi-neutrality conditions in the whole exospheric plasma. The asymptotic behavior for large radial distances as well as in the neighbourhood of the baropause has been calculated and discussed. It has been deduced that the electric field distribution near the baropause does practically not influence the properties at 1AU. A simple relationship between the coronal temperature and Solar Wind velocity at large radial distances has been found ; the kinetic plasma pressure is found to decrease asymptotically to zero as r -> oo : the parallel and perpendicular temperatures of the protons satisfy the " adiabatic approximation " of Chew, Goldberger and Low in the most external regions (r > 100 Rs). The use of this approximation between 6 — 7RS and 100 Rs would give a 250 % underestimation of the parallel proton temperature compared to the present model calculation.