激波在行星际介质中的能量耗散

THE ENERGY DEPOSITION OF A MHD SHOCK IN THE INTERPLANETARY MEDIUM

导出激波下游介质相对上游介质能流通量增量公式，并由ＨｅｌｉｏｓＡ，Ｂ飞船太阳风观测资料得出不同流速太阳风流中各参量随日心距的幂律变化．以此作为背景值分别计算出磁能、内能、动能和总能在不同日心距离处的能量耗散率．结果指出激波后介质以动能增加为主，内能次之，磁能最少；总能耗率在近日处较大，但下降较快．从０．３—１．０ＡＵ，不同强度激波总能耗随初始Ａｌｆｖｅｎ激波数Ａ１０增大而增大，对Ａ１０从２．０—１０．０的计算结果与观测值一致．

The relation of energy flux increment in downstream of a MHD shock relative to the upstream are deduced, and the radial evolution of the parameters of the solar wind in different flow speed is given in the form of power-law from the data observed by spacecrafts Helios A, B. Using above power-law of solar wind parameters as the upstream medium parameters of a shock, the rate of energy deposition dE/dR of the shock at different heliocentric distances for magnetic energy, internal energy. kinetic energy and the total energy are computed respectively. The result shows that across a MHD fast shock the increment of kinetic energy is the most important, next is the internal energy and the magnetic energy is the least; the rate of total energy deposition is larger near the sun, but its decreasing is faster. The total energy deposition increases with the initial shock Alfven number A10 in the range of0.3-1.0 AU, and the computed values are agreeable with the observed.