较小尺度磁螺旋线管相互作用的数值研究  

Numerical Research About Interaction Between Two Tube Models Containing Spiral Magnetic Field Lines With a Little Small Length-Scale

作　　者：叶占银[1] 

机构地区：[1]中国科学院空间科学与应用研究中心,北京100190

出　　处：《空间科学学报》2008年第3期194-202,共9页Chinese Journal of Space Science

摘　　要：在子午面内,偶极子场和六极子场适当叠加得到势磁场,势磁场与太阳风长时间相互作用得到特殊的冕流背景结构.在这种背景结构下,两个较小尺度的磁螺旋线管模型能够连续浮入到计算域,在计算域内相互作用,触发了日冕物质抛射(CME).在数值模拟这一过程时,较小尺度的磁螺旋线管模型具有同心圆形磁场结构,模型中心等离子压强与边界压强之比m=2,模型的半径分别取为a=0.07R_s和a=0.1R_s(R_s为太阳半径).在这两种情况下,得到了两种典型的计算结果.当a=0.07 R_s时,两个磁螺旋线管模型相互作用,在7 R_s内融合成一个磁螺旋线管模型,向外传播;当a=0.1 R_s时,两个磁螺旋线管模型相互作用,作为一个整体向外传播,在计算域内没有融合到一起,基本上保持各自的磁场结构.After a long time interaction, governed by the magnetohydrodynamic （MHD） equations, between the Parker solar wind flow and a potential magnetic field combined by a dipole and a hexapole, a special streamer background structure in the solar meridian plane is presented. With the background structure, two tube models containing spiral magnetic field lines with a small length-scale can move in the computational domain step by step, interact afterward and trigger a Coronal Mass Ejection （CME） finally. The tube model is approached by a structure made up of two-dimensional co-circular magnetic field lines, with a ratio of the plasma pressure at its center to that at its edge m = 2 and with a radius a for two cases： a = 0.07Rs （Rs is the solar radius） and a = OARs respectively. Corresponding to the two cases, two typical numerical results are obtained. In the case a = 0.07Rs, the two tube models interact with each other, merge into one set of co-circular magnetic field lines in seven solar radii and propagate outward. In the other case a = 0.1 Rs, the two tube models do not merge into one and keep two sets of co-circular magnetic field lines exist in the computational domain during their propagation as a whole.

关 键 词：太阳风 日冕物质抛射 MHD方程组 

分 类 号：P353[天文地球—空间物理学]