土星磁层顶的Kelvin-Helmholtz不稳定性和磁流体表面波

本文采用可压缩磁流体力学近似并选取Voyager-1的观测数据,讨论了土星磁层顶的Kelvin-Helmholtz不稳定性和磁流体表面波.计算表明,土星磁层随星体自转同磁鞘流之间的速度差,可以在地方时午前、中午和距中午不远的午后磁层顶激发不稳定性;午前和午后区有很强的非对称性.计算所得的波的特性与观测一致.

Kelvin-helmholtz Instability and MHD Surface Waves on Saturn's Magnetopause

The surface waves on Saturn's magnetopause are studied by examining the Kelvin-Hel-mholtz (K-H) instability at the interface between the magnetosheath and the magnetosp-here. It is demonstrated that the relative motion between corotating magnetospheric plasma and flowing magnetosheath plasma can provide free energy to generate the K-Hinstability at the magnetopause. On the afternoon side, the closer to the subsolar point, the more unstable is the magnetopause; and the instability conditions are satisfied most easily in the morning region. Using the MHD approximation and for parameters selected to represent the Voyager-1 inbound magnetopause crossing at Saturn, the wave characteristics which are in good agreement with the corresponding estimated values of observations reported by Lep-ping et al. (1981) is obtained.