PONDEROMOTIVE ACCELERATION IN CORONAL LOOPS
PONDEROMOTIVE ACCELERATION IN CORONAL LOOPS
复制标题
冠状环中的重动力加速
DOI：
10.3847/0004-637x/831/2/160
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
K. Obenschain
中科院分区：
文献类型：
--
作者：
R. Dahlburg;J. Laming;B. Taylor;K. Obenschain
有质动力加速度被认为是第一电离势（FIP）效应的原因之一，众所周知，在FIP小于10 eV的日冕中，元素的丰度比光球值增加了3-4倍。这里通过数值模拟表明，有质动力加速度发生在太阳日冕环中，具有适当的幅度和方向，作为日冕加热的“副产品”。数值模拟与HYPERION代码，它解决了完全可压缩的三维磁流体动力学方程，包括非线性热传导和光学薄辐射。数值模拟日冕环的轴向磁场从0.005到0.02 T和长度从25,000到75,000公里。在模拟中，轴向回路磁场的足点通过随机的大规模运动进行对流。存在场对准电流片的连续形成和消散，其作用是加热回路。由于日冕磁场重联，小规模的高速喷流形成。熟悉的涡旋四极子在重联点形成。在磁足点和日冕之间，重联流与边界流汇合。有质动力加速度就是在这个区域发生的。与日冕重联的性质相似，有质动力加速度也是间歇性的。
Ponderomotive acceleration has been asserted to be a cause of the first ionization potential (FIP) effect, the well-known enhancement in abundance by a factor of 3–4 over photospheric values of elements in the solar corona with FIP less than about 10 eV. It is shown here by means of numerical simulations that ponderomotive acceleration occurs in solar coronal loops, with the appropriate magnitude and direction, as a “by-product” of coronal heating. The numerical simulations are performed with the HYPERION code, which solves the fully compressible three-dimensional magnetohydrodynamic equations including nonlinear thermal conduction and optically thin radiation. Numerical simulations of coronal loops with an axial magnetic field from 0.005 to 0.02 T and lengths from 25,000 to 75,000 km are presented. In the simulations the footpoints of the axial loop magnetic field are convected by random, large-scale motions. There is a continuous formation and dissipation of field-aligned current sheets, which act to heat the loop. As a consequence of coronal magnetic reconnection, small-scale, high-speed jets form. The familiar vortex quadrupoles form at reconnection sites. Between the magnetic footpoints and the corona the reconnection flow merges with the boundary flow. It is in this region that the ponderomotive acceleration occurs. Mirroring the character of the coronal reconnection, the ponderomotive acceleration is also found to be intermittent.
DOI：
10.1088/0004-637x/797/1/7
发表时间：
2014-11
期刊：
The Astrophysical Journal
影响因子：
--
作者：
Jiajia Liu;S. McIntosh;I. De Moortel;J. Threlfall;C. Bethge
通讯作者：
Jiajia Liu;S. McIntosh;I. De Moortel;J. Threlfall;C. Bethge