Ion–neutral Interactions and Nonequilibrium Ionization in the Solar Chromosphere
Ion–neutral Interactions and Nonequilibrium Ionization in the Solar Chromosphere
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DOI：
10.3847/1538-4357/ab643f
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发表时间：
2019-12
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通讯作者：
J. Martínez-Sykora;J. Leenaarts;B. De Pontieu;D. Nóbrega-Siverio;V. Hansteen;M. Carlsson;M. Szydlarski
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文献类型：
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作者：
J. Martínez-Sykora;J. Leenaarts;B. De Pontieu;D. Nóbrega-Siverio;V. Hansteen;M. Carlsson;M. Szydlarski
色球的热结构是通过各种加热过程、辐射冷却和等离子体电离程度的复杂相互作用来调节的。在此，我们研究了氢和氦的非平衡电离（NEI）和离子中性相互作用对色球热性能的影响。我们使用Bifrost代码进行了2.5D辐射磁流体动力学模拟。该模型通过求解氢和氦的广义欧姆定律（GOL）和NEI，包括离子中性相互作用效应。GOL方程包括双极性扩散和霍尔项。我们将这种模拟与另一种计算局域热力学平衡（LTE）电离的模拟进行了比较，其中包括离子中性相互作用效应。我们的数值模型揭示了磁声激波、激波后的尾迹、针状体、低洼磁环和过渡区域的巨大热差异。特别是，我们发现，在NEI条件下，通过激波尾迹中的双极性扩散加热的效率大大降低，而在激波锋面本身，它比假设LTE时更有效。
The thermal structure of the chromosphere is regulated through a complex interaction of various heating processes, radiative cooling, and the ionization degree of the plasma. Here, we study the impact on the thermal properties of the chromosphere when including the combined action of nonequilibrium ionization (NEI) of hydrogen and helium and ion–neutral interaction effects. We have performed a 2.5D radiative magnetohydrodynamic simulation using the Bifrost code. This model includes ion–neutral interaction effects by solving the generalized Ohm’ s law (GOL) as well as NEI for hydrogen and helium. The GOL equation includes ambipolar diffusion and the Hall term. We compare this simulation with another simulation that computes the ionization in local thermodynamic equilibrium (LTE) including ion–neutral interaction effects. Our numerical models reveal substantial thermal differences in magneto-acoustic shocks, the wake behind the shocks, spicules, low-lying magnetic loops, and the transition region. In particular, we find that heating through ambipolar diffusion in shock wakes is substantially less efficient, while in the shock fronts themselves it is more efficient, under NEI conditions than when assuming LTE.