Nonequilibrium and current sheet formation in line-tied magnetic fields
Nonequilibrium and current sheet formation in line-tied magnetic fields
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线绑磁场中的非平衡和电流片形成
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
Ashis Bhattacharjee
中科院分区：
文献类型：
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作者：
C. Ng;Ashis Bhattacharjee
日冕加热模型[j]。N.帕克，天体物理学。[j] [j], 2004 (2) [j]。结果表明，对于给定的两个端板之间的平滑脚点映射，在两个端板之间的磁场线系在一起时，最多可以有一个平滑的静磁平衡。如果这样的平滑平衡由于进一步的足点运动而不断变形，使其变得不稳定，则没有其他平滑平衡供等离子体松弛，并且系统趋向于包含奇异电流（“电流片”）的非平衡状态。结果表明，当系统渐近松弛到最小能量状态时（可能在无限时间内），这一过程就会发生。给出了从包含电流层的光滑初始条件出发的数值模拟。当电流层由于脚点运动而变得越来越强烈并最终越过不稳定阈值时，模拟中观察到的磁弛豫显示出…
Parker’s model of coronal heating [E. N. Parker, Astrophys. J. 174, 499 (1972)] is considered within the framework of ideal reduced magnetohydrodynamics. It is shown that there can be at most one smooth magnetostatic equilibrium for a given smooth footpoint mapping between two end plates to which field lines are line-tied. If such a smooth equilibrium is deformed continuously by further footpoint motion so that it becomes unstable, there is no other smooth equilibrium for the plasma to relax to, and the system tends to a nonequilibrium state containing singular currents (“current sheets”). It is shown that this process can occur as the system relaxes asymptotically to a state of minimum energy (possibly in infinite time). Numerical simulations that begin from smooth initial conditions containing current layers are presented. As the current layers become increasingly intense due to footpoint motion and eventually cross a threshold for instability, the magnetic relaxation observed in the simulation shows a ...