The Mechanism for Accelerating and Heating the High Speed Solar Wind Between 0.3AU and 1AU

The momentum and energy equations for the high speed solar wind, which include all kinds of possible acceleration and heating processes, are examined simultaneously by using Helios'observations of protons and MHDfluctuations in the high speed wind ranging from 1 AUto 0.3 AU. The estimation shows that the viscous effect can not be represented by the classical expression of viscosity, which is derived from the collision-dominated plasma. It is suggested that in the region (at least) between 0.3AU and 1AUthe high speed wind acceleration by thermal pressure gradients is comparaline to that by Alfven wave pressure gradient, the acceleration by the Lorentz force of the background field is neglegible. As for the deceleration and heating, others are needed to include in addition to the solar gravity and Alfven wave heating. The function of viscosity is just both decelerating and heating, therefore the reexamination of viscous effect in the high speed wind appears to be worthwhile.