The Parker or field line tangling model of coronal heating is studied comprehensively via long-time high-resolution simulations of the dynamics of a coronal loop in cartesian geometry within the framework of reduced magnetohydrodynamics (RMHD). Slow photospheric motions induce a Poynting flux which saturates by driving an anisotropic turbulent cascade dominated by magnetic energy. In physical space this corresponds to a magnetic topology where magnetic field lines are barely entangled, nevertheless current sheets (corresponding to the original tangential discontinuities hypothesized by Parker) are continuously formed and dissipated.
Current sheets are the result of the nonlinear cascade that transfers energy from the scale of convective motions ($\sim 1,000 km$) down to the dissipative scales, where it is finally converted to heat and/or particle acceleration. Current sheets constitute the dissipative structure of the system, and the associated magnetic reconnection gives rise to impulsive ``bursty'' heating events at the small scales. This picture is consistent with the slender loops observed by state-of-the-art (E)UV and X-ray imagers which, although apparently quiescent, shine bright in these wavelengths with little evidence of entangled features.
The different regimes of weak and strong MHD turbulence that develop, and their influence on coronal heating scalings, are shown to depend on the loop parameters, and this dependence is quantitatively characterized: weak turbulence regimes and steeper spectra occur in {\it stronger loop fields} and lead to {\it larger heating rates} than in weak field regions.
The Sun as a MHD generator: application of a new heating mechanism for the coronal loops and closed magnetic structures
我们研究了太阳风（加上其他可能存在的流动）穿过磁场线（垂直于流动）加热太阳日冕活动区域中的环路和其他闭合磁结构的可能性，其方式与传统MHD发电机的工作方式类似。一个简单的模型，制定允许计算由这种机制产生的典型电流。这使得能够判断太阳能活动区的环路是否可以通过所提出的机制通过相关的欧姆耗散加热。它表明，即使加热区的宽度是几个质子拉莫尔半径的数量级，（这实际上意味着环由{ \it纳米线}表示，通过与纳米耀斑日冕加热机制类比，具有几个质子拉莫尔半径的宽度）并且等离子体流速为50 km s $^{-1}$，则仅约1%根据这一猜想，可以满足日冕环的加热要求。该模型的其他影响，如预测的空间热分布沿环以及应用模型的其他地方，如色球层和共转相互作用区域结构的太阳风进行了讨论。
