Collisionless model of the solar wind in a spiral magnetic field

We present a kinetic collisionless model of the solar wind generalized to t ake into account the spiral structure of the interplanetary magnetic field. This model, which also includes Kappa velocity distributions, calculates s elf-consistently the electric potential profile and derives the solar wind speed and the temperatures of the medium. We study how the inclusion of the spiral geometry changes the plasma parameters compared to the case of a ra dial magnetic field. Whereas the interplanetary electric potential, the win d density and bulk speed are not significantly changed, we show that the el ectron and proton temperatures are modified; in particular, we find a decre ase of the proton temperature and of its anisotropy, and an increase of the electron temperature. We discuss these results and the validity of the mod el.