Numerical simulations of conversion to Alfvén waves in solar active regions
Numerical simulations of conversion to Alfvén waves in solar active regions
复制标题
太阳活动区阿尔文波转换的数值模拟
DOI：
10.1088/1742-6596/271/1/012042
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
P. Cally
中科院分区：
文献类型：
--
作者：
E. Khomenko;P. Cally
我们使用2.5D数值模拟研究了磁声波与Alvén波的耦合。在我们的实验中，一个给定频率和波数的快速磁声波产生的表面以下。假设域内的磁场是均匀的和倾斜的。在声速和阿尔芬速度相等的层附近，测量转换为阿尔芬波的效率，计算它们的能通量。磁场振荡和速度振荡之间的特殊振幅和相位关系有助于我们证明，经过变换并到达高层大气后产生的波确实是阿尔文波。我们发现，从快磁声波到阿尔文波的转换是特别重要的倾角θ和方位角的磁场的夹角在55和65度之间，与最大值移动到较大的倾角为较低的频率波。传输到高层大气的最大Alfvén通量大约比相应的声通量低2-3倍。
We study the coupling of magneto-acoustic waves to Alvén waves using 2.5D numerical simulations. In our experiment, a fast magnetoacoustic wave of a given frequency and wavenumber is generated below the surface. The magnetic field in the domain is assumed homogeneous and inclined. The efficiency of the conversion to Alfvén waves near the layer of equal acoustic and Alfven speeds is measured calculating their energy flux. The particular amplitude and phase relations between the oscillations of magnetic field and velocity help us to demonstrate that the waves produced after the transformation and reaching upper atmosphere are indeed Alfvén waves. We find that the conversion from fast magneto-acoustic waves to Alfvén waves is particularly important for the inclination θ and azimuth ϕ angles of the magnetic field between 55 and 65 degrees, with the maximum shifted to larger inclinations for lower frequency waves. The maximum Alfvén flux transmitted to the upper atmosphere is about 2-3 times lower than the corresponding acoustic flux.