Energy Release in Driven Twisted Coronal Loops
Energy Release in Driven Twisted Coronal Loops
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DOI：
10.1007/s11207-015-0824-7
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发表时间：
2016-01-01
期刊：
影响因子：
2.8
通讯作者：
Hood, A. W.
中科院分区：
文献类型：
--
作者：
Bareford, M. R.;Gordovskyy, M.;Hood, A. W.
我们研究代表冠状环的扭曲磁通量管中的磁重联。主要目标是确定场几何形状和各种热力学效应对扭曲磁通管稳定性以及加热区域的尺寸和分布的影响。特别是，我们的目的是研究基于最初的圆柱形对称磁通管的早期理想化模型与更现实的模型有多大不同，包括大尺度曲率、大气分层、热传导和其他效应。此外，我们还比较了扭转环中磁重联过程中欧姆加热和冲击加热在能量转换中的作用。具有直通量管的模型在重新连接过程中显示出类似的加热等离子体分布：它最初形成螺旋形状，随后变得非常破碎。这些模型中的加热沿通量管分布相当均匀。同时，弯曲环路中的热等离子体区域是不对称的并且集中在环路顶部附近。大尺度曲率会产生不稳定影响：较小的扭曲会导致不稳定。足点收敛通常会稍微延迟不稳定，但在某些情况下，会聚磁通管可能不太稳定。最后，引入分层大气会导致波传播衰减，从而产生不稳定效应。
We investigate magnetic reconnection in twisted magnetic fluxtubes, representing coronal loops. The main goal is to establish the influence of the field geometry and various thermodynamic effects on the stability of twisted fluxtubes and on the size and distribution of heated regions. In particular, we aim to investigate to what extent the earlier idealised models, based on the initially cylindrically symmetric fluxtubes, are different from more realistic models, including the large-scale curvature, atmospheric stratification, thermal conduction and other effects. In addition, we compare the roles of Ohmic heating and shock heating in energy conversion during magnetic reconnection in twisted loops. The models with straight fluxtubes show similar distribution of heated plasma during the reconnection: it initially forms a helical shape, which subsequently becomes very fragmented. The heating in these models is rather uniformly distributed along fluxtubes. At the same time, the hot plasma regions in curved loops are asymmetric and concentrated close to the loop tops. Large-scale curvature has a destabilising influence: less twist is needed for instability. Footpoint convergence normally delays the instability slightly, although in some cases, converging fluxtubes can be less stable. Finally, introducing a stratified atmosphere gives rise to decaying wave propagation, which has a destabilising effect.