The fast solar wind

A two‐fluid model for the fast solar wind is described which attempts to account for observations at large distances and close to the Sun in coronal holes, allowing for anisotropic proton temperature, Alfven wave pressure and a realistic magnetic field, but neglecting the effects of proton heat conduction and viscosity. The resulting acceleration of the wind near the Sun is quite rapid, although somewhat less so than in our previous models where the wave pressure was neglected. The proton temperatures in the corona remain relatively high and exceed the associated wave “temperature” out to a heliocentric distance of about 5 solar radii. The proton temperature anisotropy may become very large if the effective particle scattering rate is small and it is suggested that in fact there may be significant particle‐wave scattering in the corona at least.