0.3AU和1AU之间高速太阳风的加速和加热机制

本文应用Helios飞船在0.3AU和1AU之间的高速太阳风质子和磁流涨落观测, 同时考察了包括各种可能的加速和加热效应的高速太阳风动量方程和质子能量方程.分析表明在碰撞为主的等离子体条件下导出的经典粘性系数表式明显地不适用于太阳风等离子体;在0.3AU和1AU之间主要加速力是热压梯度力和Alfven波压力, 背景磁场的洛伦兹力可忽略;在减速方面, 除了太阳重力外, 还需存在其它减速机制, 才能使太阳风动量平衡.看来唯有粘性能同时满足减速和加热这两种要求. 

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.