Collisional ionisation, recombination, and ionisation potential in two-fluid slow-mode shocks: Analytical and numerical results
Collisional ionisation, recombination, and ionisation potential in two-fluid slow-mode shocks: Analytical and numerical results
复制标题
二流体慢模式激波中的碰撞电离、复合和电离势：分析和数值结果
DOI：
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发表时间：
2020
影响因子：
6.5
通讯作者：
A. Hillier
中科院分区：
文献类型：
--
作者：
Ben Snow;A. Hillier
上下文冲击是温暖等离子体环境的普遍特征，例如太阳低层大气和分子云，其中包括电离和中性物质。包括部分电离导致存在一个有限的宽度的冲击，电离和中性物种去耦和再耦合。因此，漂移速度存在于激波内，导致两种物质之间的摩擦加热，除了跨越激波的绝热温度变化之外。激波内局部温度的提高改变了复合和电离速率，从而改变了等离子体的组成。
目标。我们研究碰撞电离和重组慢模式部分电离冲击的作用。特别是，我们将电离势能损失和分析的后果，有一个非保守的能量方程。
方法.一个半解析的方法是用来确定可能的平衡激波跳跃的两个流体模型电离，重组，电离势，和任意加热。使用（PIP）代码进行双流体数值模拟。结果进行了比较的磁流体动力学（MHD）模型和半解析解。
结果占电离，重组和电离电位显着改变了冲击的行为在两个子结构和冲击后的地区。特别地，对于给定的温度，由于辐射损失需要通过加热函数来平衡，因此平衡只能存在于特定的密度。电离势的一个结果是，压缩激波将导致激波后区域的温度降低，而不是像MHD那样升高。数值模拟配对以及与推导出的冲击波速度的分析模型。
结论多流体效应可能导致MHD结果的显著偏离。本文的结果适用于广泛的部分电离等离子体，包括太阳色球和分子云。
Context. Shocks are a universal feature of warm plasma environments, such as the lower solar atmosphere and molecular clouds, which consist of both ionised and neutral species. Including partial ionisation leads to the existence of a finite width for shocks, where the ionised and neutral species decouple and recouple. As such, drift velocities exist within the shock that lead to frictional heating between the two species, in addition to adiabatic temperature changes across the shock. The local temperature enhancements within the shock alter the recombination and ionisation rates and hence change the composition of the plasma.
Aims. We study the role of collisional ionisation and recombination in slow-mode partially ionised shocks. In particular, we incorporate the ionisation potential energy loss and analyse the consequences of having a non-conservative energy equation.
Methods. A semi-analytical approach is used to determine the possible equilibrium shock jumps for a two-fluid model with ionisation, recombination, ionisation potential, and arbitrary heating. Two-fluid numerical simulations are performed using the (PIP) code. Results are compared to the magnetohydrodynamic (MHD) model and the semi-analytic solution.
Results. Accounting for ionisation, recombination, and ionisation potential significantly alters the behaviour of shocks in both substructure and post-shock regions. In particular, for a given temperature, equilibrium can only exist for specific densities due to the radiative losses needing to be balanced by the heating function. A consequence of the ionisation potential is that a compressional shock will lead to a reduction in temperature in the post-shock region, rather than the increase seen for MHD. The numerical simulations pair well with the derived analytic model for shock velocities.
Conclusion. Multi-fluid effects can lead to a significant departure from MHD results. The results in this paper are applicable to a wide range of partially ionised plasmas, including the solar chromosphere and molecular clouds.
日珥中离子和中性原子的多普勒速度之间的差异
影响因子：
6.5
作者：
Anan T
通讯作者：
Anan T
部分电离等离子体中重连接驱动的慢模激波的形成和演化
DOI：
10.48550/arxiv.1602.01112
发表时间：
2016
期刊：
--
影响因子：
--
作者：
Hillier A
通讯作者：
Hillier A