Collisional ionization and recombination effects on coalescence instability in chromospheric partially ionized plasmas
Collisional ionization and recombination effects on coalescence instability in chromospheric partially ionized plasmas
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DOI：
10.1063/5.0087667
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发表时间：
2022-05
影响因子：
2.2
通讯作者：
G. Murtas;A. Hillier;B. Snow
中科院分区：
文献类型：
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作者：
G. Murtas;A. Hillier;B. Snow
类等离子体介导的快速磁场重联在驱动爆炸动力学和加热方面起着重要作用，但对它在太阳色球部分电离等离子体（PIP）中的发展知之甚少。部分电离可能会在很大程度上改变聚结不稳定性的动力学，从而促进快速重联，并通过等离子体相互作用形成湍流重联电流片，但目前还不清楚PIP效应在多大程度上影响这一过程。我们研究的作用，碰撞电离和重组的发展中的等离子体团合并PIP通过2.5D模拟的双流体模型。其目的是了解这些双流体耦合过程是否在加速重连中发挥作用。我们发现，在一般情况下，电离-复合过程减慢聚结。与Murtas等人[Phys. Plasmas 28，032901（2021）]中仅包括热碰撞的先前模型不同，电离和复合稳定了电流片并抑制了非线性动力学，在有限的情况下发生湍流重连：电离的爆发导致形成更厚的电流片，即使在包括辐射损失以冷却系统时也是如此。因此，聚结时间尺度对电离-复合过程非常敏感。然而，PIP中的重联仍然比具有相同堆密度的完全电离等离子体环境中的重联更快：PIP重联率（[公式：见文本]）相对于MHD重联率（[公式：见文本]）增加了[公式：见文本]的因子。
Plasmoid-mediated fast magnetic reconnection plays a fundamental role in driving explosive dynamics and heating, but relatively little is known about how it develops in partially ionized plasmas (PIP) of the solar chromosphere. Partial ionization might largely alter the dynamics of the coalescence instability, which promotes fast reconnection and forms a turbulent reconnecting current sheet through plasmoid interaction, but it is still unclear to what extent PIP effects influence this process. We investigate the role of collisional ionization and recombination in the development of plasmoid coalescence in PIP through 2.5D simulations of a two-fluid model. The aim is to understand whether these two-fluid coupling processes play a role in accelerating reconnection. We find that, in general, the ionization–recombination process slows down the coalescence. Unlike the previous models in Murtas et al. [Phys. Plasmas 28, 032901 (2021)] that included thermal collisions only, ionization and recombination stabilize current sheets and suppress non-linear dynamics, with turbulent reconnection occurring in limited cases: bursts of ionization lead to the formation of thicker current sheets, even when radiative losses are included to cool the system. Therefore, the coalescence timescale is very sensitive to ionization–recombination processes. However, reconnection in PIP is still faster than in a fully ionized plasma environment having the same bulk density: the PIP reconnection rate ([Formula: see text]) increases by a factor of [Formula: see text] with respect to the MHD reconnection rate ([Formula: see text]).