Chromospheric evaporation and phase mixing of Alfvén waves in coronal loops
Chromospheric evaporation and phase mixing of Alfvén waves in coronal loops
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日冕环中阿尔文波的色球层蒸发和相位混合
DOI：
10.1051/0004-6361/201937266
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发表时间：
2020
影响因子：
6.5
通讯作者：
Van Damme H
中科院分区：
文献类型：
--
作者：
Van Damme H
作为一种可能的日冕加热机制，alfvsamn波的相位混合已被广泛研究，但尚未考虑到自洽的全部热力学后果。有人认为，在某些情况下，加热的热力学反馈可以实质性地影响横向密度梯度，甚至抑制相混合过程。摘要本文首次采用磁流体动力学（MHD）模拟方法，引入适当的热力学项，量化了alfvsamn波在日冕环内相混合加热后的蒸发及其对横向密度分布的影响。方法采用拉格朗日Remap代码Lare2D进行数值模拟。我们建立了一个二维循环模型，包括场对齐的热力学平衡和跨场（背景）加热剖面。实现了一种连续的、正弦的、高频的alfvvac波形驱动器。当alfvn波沿场传播时，由于环路日冕部分的交叉场密度梯度，它们经历相位混合。我们研究了场向流的存在，相位混合alfvsamn波的耗散加热，以及随后低层大气的蒸发。结果我们发现alfvsamn波的相位混合导致环壳区域的适度加热，色球物质蒸发到日冕中，上升流仅为5-20 m s−1。虽然蒸发导致环壳区域的质量增加，但对密度梯度的影响，从而对相混合过程的影响是微不足道的。结论本文自一致地研究了色球蒸发对日冕环中交叉场密度梯度和相位混合过程的影响。我们发现，在我们的特定设置（小振幅，高频波）的影响太小，不能显著改变密度梯度。
ContextPhase mixing of Alfvén waves has been studied extensively as a possible coronal heating mechanism but without the full thermodynamic consequences considered self-consistently. It has been argued that in some cases, the thermodynamic feedback of the heating could substantially affect the transverse density gradient and even inhibit the phase mixing process.AimsIn this paper, for the first time, we use magnetohydrodynamic (MHD) simulations with the appropriate thermodynamical terms included to quantify the evaporation following heating by phase mixing of Alfvén waves in a coronal loop and the effect of this evaporation on the transverse density profile.MethodsThe numerical simulations were performed using the Lagrangian Remap code Lare2D. We set up a 2D loop model consisting of a field-aligned thermodynamic equilibrium and a cross-field (background) heating profile. A continuous, sinusoidal, high-frequency Alfvén wave driver was implemented. As the Alfvén waves propagate along the field, they undergo phase mixing due to the cross-field density gradient in the coronal part of the loop. We investigated the presence of field-aligned flows, heating from the dissipation of the phase-mixed Alfvén waves, and the subsequent evaporation from the lower atmosphere.ResultsWe find that phase mixing of Alfvén waves leads to modest heating in the shell regions of the loop and evaporation of chromospheric material into the corona with upflows of the order of only 5–20 m s−1. Although the evaporation leads to a mass increase in the shell regions of the loop, the effect on the density gradient and, hence, on the phase mixing process, is insignificant.ConclusionsThis paper self-consistently investigates the effect of chromospheric evaporation on the cross-field density gradient and the phase mixing process in a coronal loop. We found that the effects in our particular setup (small amplitude, high frequency waves) are too small to significantly change the density gradient.
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模拟日冕加热增强的色球蒸发的新方法 - II。
DOI：
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发表时间：
2017
期刊：
影响因子：
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作者：
C. Johnston;A. Hood;P. Cargill;I. Moortel
通讯作者：
I. Moortel
太阳过渡区域发出的光谱线的红移、宽度和辐射度
DOI：
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发表时间：
2011
期刊：
影响因子：
--
作者：
U. Feldman;I. Dammasch;G. Doschek
通讯作者：
G. Doschek
DOI：
10.1088/0004-637x/769/1/47
发表时间：
2013
期刊：
The Astrophysical Journal
影响因子：
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作者：
Nuno Guerreiro;V. Hansteen;B. Pontieu
通讯作者：
B. Pontieu
影响因子：
6.5
作者：
E. Verwichte;P. Antolin;G. Rowlands;P. Kohutova;T. Neukirch
通讯作者：
E. Verwichte;P. Antolin;G. Rowlands;P. Kohutova;T. Neukirch
使用自适应传导方法对太阳过渡区域进行建模
影响因子：
6.5
作者：
C. Johnston;P. Cargill;A. Hood;I. Moortel;Stephen J. Bradshaw;A. C. Vaseekar
通讯作者：
A. C. Vaseekar