Dynamics of shear velocity layer with bent magnetic field lines
Dynamics of shear velocity layer with bent magnetic field lines
复制标题
具有弯曲磁场线的剪切速度层动力学
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
B. Sonnerup
中科院分区：
文献类型：
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作者：
V. Galinsky;B. Sonnerup
本文采用全三维磁流体动力学方法，模拟了在横向磁场中具有弯曲磁力线的速度剪切等离子体流动。“类电离层”边界条件用于闭合场向电流，两个电离层由具有恒定电阻率的导电板表示。与具有均匀横向磁场的标准平面2D情况相比，Kelvin-Helmholtz不稳定性的增长率随着弯曲的增加而显著下降。在代表地球低纬度边界层的条件下，如果磁力线弯曲足够强，则磁力线张力可以完全抑制不稳定性。对于弱弯曲，撕裂模不稳定性和Kelvin-Helmholtz不稳定性的组合导致形成局部三维电流/涡流管，其电离层足迹是维京海盗卫星观测到的极光亮点的可能模型。
A fully three-dimensional, magnetohydro-dynamic simulation of velocity-sheared plasma flow in an ambient transverse magnetic field with bent magnetic field lines has been performed. “Ionospheric-like” boundary conditions were used for closing field-aligned currents, the two ionospheres being represented by conducting plates with constant resistivity. Compared to the standard plane 2D case with a uniform transverse magnetic field, the growth rate of the Kelvin-Helmholtz instability drops significantly as bending increases. Under conditions representative of the Earth's low latitude boundary layer, the instability may be suppressed completely by the magnetic field-line tension if the field-line bending is sufficiently strong. For weak bending, a combination of the tearing mode instability and the Kelvin-Helmholtz instability leads to the formation of localized 3D current/vortex tubes, the ionospheric foot prints of which are possible models of the auroral bright spots observed by the Viking satellite.