Coronal Heating by the Resonant Absorption of Alfven Waves: Importance of the Global Mode and Scaling Laws
Coronal Heating by the Resonant Absorption of Alfven Waves: Importance of the Global Mode and Scaling Laws
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阿尔文波共振吸收引起的日冕加热：全局模式和标度定律的重要性
DOI：
10.1086/173169
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
J. Davila
中科院分区：
文献类型：
--
作者：
R. S. Steinolfson;J. Davila
本文用完全可压缩、低β、电阻等离子体的MHD方程数值模拟研究了日冕活动区环加热的共振吸收过程。与更近似的解析模型的比较表明，解析理论的主要预测，在很大程度上，证实了数值计算。模拟结果表明，耗散主要发生在一个薄的谐振层。通过模拟验证的一些分析预测的功能是（a）初始不均匀性内的谐振层的位置;（B）大范围的循环密度的全局模式的重要性;（c）谐振层厚度和稳态加热速率对耗散系数的依赖性;以及（d）谐振层形成所需的时间。与以前的一些分析和模拟结果相比，环路达到稳态的时间被发现是相混合时间，而不是耗散时间。这种分歧是由于忽略了存在的全球模式在一些早期的分析。共振吸收过程也表现出类似于一个经典的驱动谐振子。
Numerical simulations of the MHD equations for a fully compressible, low-beta, resistive plasma are used to study the resonance absorption process for the heating of coronal active region loops. Comparisons with more approximate analytic models show that the major predictions of the analytic theories are, to a large extent, confirmed by the numerical computations. The simulations demonstrate that the dissipation occurs primarily in a thin resonance layer. Some of the analytically predicted features verified by the simulations are (a) the position of the resonance layer within the initial inhomogeneity; (b) the importance of the global mode for a large range of loop densities; (c) the dependence of the resonance layer thickness and the steady-state heating rate on the dissipation coefficient; and (d) the time required for the resonance layer to form. In contrast with some previous analytic and simulation results, the time for the loop to reach a steady state is found to be the phase-mixing time rather than a dissipation time. This disagreement is shown to result from neglect of the existence of the global mode in some of the earlier analyses. The resonant absorption process is also shown to behave similar to a classical driven harmonic oscillator.