FAST MAGNETIC RECONNECTION IN THE SOLAR CHROMOSPHERE MEDIATED BY THE PLASMOID INSTABILITY
FAST MAGNETIC RECONNECTION IN THE SOLAR CHROMOSPHERE MEDIATED BY THE PLASMOID INSTABILITY
复制标题
DOI：
10.1088/0004-637x/799/1/79
复制
发表时间：
2015-01
期刊：
影响因子：
--
通讯作者：
Lei Ni;B. Kliem;Jun Lin;N. Wu
中科院分区：
文献类型：
--
作者：
Lei Ni;B. Kliem;Jun Lin;N. Wu
利用2.5维磁流体动力学模拟方法研究了部分电离太阳色球层中的磁场重联现象，包括辐射冷却和双极扩散。一个哈里斯电流片和没有一个指导领域被认为是。在本模拟中，中色球层参数的特征值意味着高磁雷诺数为106-107。快速磁场重联，然后发展作为等离子体团不稳定性的结果，而不需要调用异常电阻率增强。随着不稳定性级联到更小的尺度（接近离子惯性长度），多个级别的不稳定性随之而来。在整个级联等离子体团形成过程中，对于零和强引导场，标准化为流入区域磁场和Alfvén速度的渐近值的重联率达到范围为0.01-0.03的值。流出速度达到1040 km s-1。慢模激波从X点延伸，将等离子体团加热到108 × 104 K。在零引导场的情况下，包含双极扩散和辐射冷却导致电流片的快速变薄（下至30 μ m）和次级岛的早期形成。这两个过程对强引导场的等离子体团不稳定性的影响很小。垂直电流片的重联率、温度增强和向上流出速度与色球喷流的特征值对应良好。
Magnetic reconnection in the partially ionized solar chromosphere is studied in 2.5 dimensional magnetohydrodynamic simulations including radiative cooling and ambipolar diffusion. A Harris current sheet with and without a guide field is considered. Characteristic values of the parameters in the middle chromosphere imply a high magnetic Reynolds number of ∼106–107 in the present simulations. Fast magnetic reconnection then develops as a consequence of the plasmoid instability without the need to invoke anomalous resistivity enhancements. Multiple levels of the instability are followed as it cascades to smaller scales, which approach the ion inertial length. The reconnection rate, normalized to the asymptotic values of magnetic field and Alfvén velocity in the inflow region, reaches values in the range ∼0.01–0.03 throughout the cascading plasmoid formation and for zero as well as for strong guide field. The outflow velocity reaches ≈40 km s−1. Slow-mode shocks extend from the X-points, heating the plasmoids up to ∼8 × 104 K. In the case of zero guide field, the inclusion of both ambipolar diffusion and radiative cooling causes a rapid thinning of the current sheet (down to ∼30 m) and early formation of secondary islands. Both of these processes have very little effect on the plasmoid instability for a strong guide field. The reconnection rates, temperature enhancements, and upward outflow velocities from the vertical current sheet correspond well to their characteristic values in chromospheric jets.