Intermediate shock sub-structures within a slow-mode shock occurring in partially ionised plasma
Intermediate shock sub-structures within a slow-mode shock occurring in partially ionised plasma
复制标题
部分电离等离子体中发生的慢模式激波中的中间激波子结构
DOI：
10.1051/0004-6361/201935326
复制
发表时间：
2019
影响因子：
6.5
通讯作者：
A. Hillier
中科院分区：
文献类型：
--
作者：
B. Snow;A. Hillier
上下文慢模冲击对于了解太阳大气中的快速磁重联、喷流形成和加热以及其他天体物理系统非常重要。太阳色球层的大气条件允许电离粒子和中性粒子存在并相互作用。在这样的条件下，精细的子结构存在于慢模冲击由于等离子体和中性物质的去耦和再耦合。
目标。我们数值研究了部分电离等离子体中慢模激波内的精细子结构，特别是分析了慢模激波内中间跃迁的形成。
方法.高分辨率的一维数值模拟进行了使用（PIP）代码使用双流体的方法。
结果我们发现，长寿命的中间（阿尔文）冲击可以形成在慢模式的冲击，那里有一个从以上的阿尔文速度和磁场反转的冲击波前的冲击过渡到以下。碰撞耦合为中性流体提供摩擦加热，导致Sedov-Taylor膨胀，在中性速度和中性密度中具有过冲。密度的增加导致阿尔文速度的降低，并且由此等离子体流入在激波的有限宽度内被加速到阿尔文速度以上，导致中间过渡。这一过程发生在很宽的物理参数范围内，对于所有研究的等离子体-β、中性分数和磁角值，都存在中间激波。随着时间的推移，磁场反转的幅度减小，因为中性压力不能平衡洛伦兹力。中间激波的寿命足够长，可以被认为是一种物理结构，与初始条件无关。
结论.中间激波是一种物理特征，由于物质之间的碰撞耦合，它可以在部分电离等离子体中作为激波子结构长时间存在。
Context. Slow-mode shocks are important in understanding fast magnetic reconnection, jet formation and heating in the solar atmosphere, and other astrophysical systems. The atmospheric conditions in the solar chromosphere allow both ionised and neutral particles to exist and interact. Under such conditions, fine sub-structures exist within slow-mode shocks due to the decoupling and recoupling of the plasma and neutral species.
Aims. We study numerically the fine sub-structure within slow-mode shocks in a partially ionised plasma, in particular, analysing the formation of an intermediate transition within the slow-mode shock.
Methods. High-resolution 1D numerical simulations were performed using the (PIP) code using a two-fluid approach.
Results. We discover that long-lived intermediate (Alfvén) shocks can form within the slow-mode shock, where there is a shock transition from above to below the Alfvén speed and a reversal of the magnetic field across the shock front. The collisional coupling provides frictional heating to the neutral fluid, resulting in a Sedov-Taylor-like expansion with overshoots in the neutral velocity and neutral density. The increase in density results in a decrease of the Alfvén speed and with this the plasma inflow is accelerated to above the Alfvén speed within the finite width of the shock leading to the intermediate transition. This process occurs for a wide range of physical parameters and an intermediate shock is present for all investigated values of plasma-β, neutral fraction, and magnetic angle. As time advances the magnitude of the magnetic field reversal decreases since the neutral pressure cannot balance the Lorentz force. The intermediate shock is long-lived enough to be considered a physical structure, independent of the initial conditions.
Conclusions. Intermediate shocks are a physical feature that can exist as shock sub-structure for long periods of time in partially ionised plasma due to collisional coupling between species.
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