A Hydrodynamic Model of Alfvénic Wave Heating in a Coronal Loop and Its Chromospheric Footpoints
A Hydrodynamic Model of Alfvénic Wave Heating in a Coronal Loop and Its Chromospheric Footpoints
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日冕环中阿尔芬波加热及其色球足点的流体动力学模型
DOI：
10.3847/1538-4357/aaa2fe
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
J. Leake
中科院分区：
文献类型：
--
作者：
J. Reep;A. Russell;L. Tarr;J. Leake
阿尔夫文波被认为是日冕环中一种重要的能量传输机制，能够将能量传递到日冕和色球层，并产生许多观测到的耀斑和静止区的特征。在以前的工作中，我们建立了波的电阻耗散（双极扩散）可以驱动强烈的色球加热和蒸发，能够产生耀斑签名。然而，该模型是基于一个简化的假设，即波立即传播到色球层，目前的工作消除了这一假设。通过射线追踪方法，我们已经实现了行波场对齐的流体动力学模拟，消散局部，因为他们传播沿着场线。我们比较这种方法，并验证对磁流体动力学代码Lare 3D。然后，我们研究的重要性旅行时间的动态环的演变，发现（1）电离水平的等离子体起着决定的位置和速度，波消散的关键作用;（2）持续时间长的波有效地在色球层中钻了一个洞，使后续波穿透得比以前预期的更深，与电子束不同，电子束的能量沉积随着蒸发减少电子的平均自由路径而在高度上上升;以及（3）与电子束的能量沉积不同，这些波的耗散驱动传播到更深深度的压力前沿。
Alfvénic waves have been proposed as an important energy transport mechanism in coronal loops, capable of delivering energy to both the corona and chromosphere and giving rise to many observed features of flaring and quiescent regions. In previous work, we established that resistive dissipation of waves (ambipolar diffusion) can drive strong chromospheric heating and evaporation, capable of producing flaring signatures. However, that model was based on a simplified assumption that the waves propagate instantly to the chromosphere, an assumption that the current work removes. Via a ray-tracing method, we have implemented traveling waves in a field-aligned hydrodynamic simulation that dissipate locally as they propagate along the field line. We compare this method to and validate against the magnetohydrodynamics code Lare3D. We then examine the importance of travel times to the dynamics of the loop evolution, finding that (1) the ionization level of the plasma plays a critical role in determining the location and rate at which waves dissipate; (2) long duration waves effectively bore a hole into the chromosphere, allowing subsequent waves to penetrate deeper than previously expected, unlike an electron beam whose energy deposition rises in height as evaporation reduces the mean-free paths of the electrons; and (3) the dissipation of these waves drives a pressure front that propagates to deeper depths, unlike energy deposition by an electron beam.
DOI：
10.3847/0004-637x/829/2/80
发表时间：
2016-01
期刊：
The Astrophysical Journal
影响因子：
--
作者：
C. Brady;T. Arber
通讯作者：
C. Brady;T. Arber
DOI：
10.3847/0004-637x/827/2/101
发表时间：
2016-05
期刊：
The Astrophysical Journal
影响因子：
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作者：
G. Kerr;L. Fletcher;A. Russell;J. Allred
通讯作者：
G. Kerr;L. Fletcher;A. Russell;J. Allred
DOI：
10.1088/0004-637x/695/2/1151
发表时间：
2009-04
期刊：
The Astrophysical Journal
影响因子：
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作者：
J. Birn;L. Fletcher;M. Hesse;T. Neukirch
通讯作者：
J. Birn;L. Fletcher;M. Hesse;T. Neukirch