太阳爆发中的精细湍流结构及重联加热过程的数值研究

太阳爆发是日冕磁结构失衡而导致的能量剧烈释放的多尺度动态学过程，其中大量的磁能是通过磁重联转换的，而这类成功的爆发则要求足够快的磁重联过程。最近对SOL2017-09-10T 16:06 UT事件的观测表明，当耀斑/CME电流片发展到足够长时，湍流在其内部发生可以显著地加快能量耗散。而我们的已展开的数值模拟也辨认出三个特征区域的湍流形态:耀斑环顶、CME底部和电流片内部。他们的共同点是能量级联都从大尺度传递到小尺度，最终被耗散掉 ;不同点是会分别呈现各向异性和各向同性的湍流特征及伴随着不同性质的激波结构，这些都跟湍流局部的分形结构息息相关。我们拟对磁流体动力学程序ATHENA进行深度开发，加入热传导和辐射冷却效应，重现一系列完整的太阳爆发过程的磁重联相关现象，旨在利用高分辨率的数值实验解释湍流在各部分的能量转化和等离子体加热中的重要作用，也进一步探讨湍流在带电粒子加速中所扮演的角色。

Solar eruption is a multi-scale dynamical process of energy release due to the loss of equilibrium for the magnetic field in the corona. Large amounts of magnetic energy (10^29-10^32 ergs) are converted into kinetic energy and thermal energy via magnetic reconnection, which also allows for particle acceleration. To support major eruptions to continue, the reconnection process generally needs to occur at a reasonably fast rate. Recent observational studies about an X8.2-class flare (SOL2017-09-10T16:06 UT) and a fast coronal mass ejection (CME) on 2017 September 10 suggest that fragmented and turbulent structures in the long stretching current sheet may help the magnetic reconnection within it proceed efficiently. Our previous simulations also recognized the turbulence at three specific parts: above the flare loops, underneath the CME and inside the current sheet, where the energy cascades from large scales to small scales and eventually dissipates. Anisotropy and quasi-isotropy of turbulence manifest at different regions along with diverse shocks, which are related to local geometries of turbulence. In this study, we are going to develop exhaustively the open-source MHD code ATHENA to perform a series of high-resolution simulations on magnetic reconnection associated to solar eruptions including thermal conduction and radiative cooling, in order to explain the role of turbulence in the energy conversion, plasma heating as well as particle acceleration.