部分电离日珥等离子体板中的耗散不稳定性：II。压缩性的影响
Dissipative instabilities in a partially ionised prominence plasma slab: II. The effect of compressibility
摘要：
本研究涉及的耗散不稳定性，出现在一个可压缩的部分电离的等离子体板嵌入在一个均匀的磁场，模拟太阳能电池的等离子体的状态。在部分电离等离子体中，主要的耗散效应是考林电阻率。板块外的区域（模拟日冕）是完全电离的，耗散的主要机制是粘性。扩展的磁流体动力学（MHD）方程的解析解被发现内部和外部的板和解决方案相匹配的边界处的板。的色散关系推导和解决方案被发现解析在细长板的限制，而出现的不稳定性的必要条件进行了研究，数值为整个参数空间。我们的研究集中在可压缩性对不稳定性的产生和演化的影响。我们发现，可压缩性降低了阈值的平衡流，波可以是不稳定的，到一个水平，这是可比的内部尖点速度，这是相同的顺序的流速，目前在太阳能电池中观察到。我们的研究只涉及慢波，因为这些是最有可能变得不稳定的扰动，然而，不稳定的时间尺度被发现是相当大的范围从$10^5$-$10^7$秒。它是确定的不稳定性阈值进一步影响的中性粒子的浓度和电晕的粘性的强度。有趣的是，后两个方面具有相反的效果。我们的数值分析表明，平衡流，中性粒子和色散之间的相互作用可以大大改变波的性质。
英文摘要：
This present study deals with the dissipative instability that appears in a compressible partially ionised plasma slab embedded in a uniform magnetic field, modelling the state of the plasma in solar prominences. In the partially ionised plasma, the dominant dissipative effect is the Cowling resistivity. The regions outside the slab (modelling the solar corona) are fully ionised, and the dominant mechanism of dissipation is viscosity. Analytical solutions to the extended magnetohydrodynamic (MHD) equations are found inside and outside of the slab and solutions are matched at the boundaries of the slab. The dispersion relation is derived and solutions are found analytically in the slender slab limit, while the conditions necessary for the appearance of the instability is investigated numerically for the entire parameter space. Our study is focussed on the effect of the compressibility on the generation and evolution of instabilities. We find that compressibility reduces the threshold of the equilibrium flow, where waves can be unstable, to a level that is comparable to the internal cusp speed, which is of the same order of flow speeds that are currently observed in solar prominences. Our study addresses only the slow waves, as these are the most likely perturbations to become unstable, however the time-scales of the instability are found to be rather large ranging from $10^5$-$10^7$ seconds. It is determined that the instability threshold is further influenced by the concentration of neutrals and the strength of the viscosity of the corona. Interestingly, these two latter aspects have opposite effects. Our numerical analysis shows that the interplay between the equilibrium flow, neutrals and dispersion can change considerably the nature of waves.
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