重新评估均匀等离子体中的热不稳定性：对不稳定性域的扩展分析
Reevaluating thermal instability in a uniform plasma: an extended analysis of instability domains
AI总结：
本研究重新评估了均匀等离子体中热不稳定性，扩展了不稳定性域的分类，并探讨了热传导对不稳定性区域的影响。
摘要：
热不稳定性在天体等离子体的动力学中起着关键作用。在G.B. Field（1965）和T. Waters及D. Proga（2019）的基础工作基础上，本研究重新审视均匀非磁性介质中的热不稳定性。我们旨在重新评估并扩展对不稳定性域的理解，重点在于加热、辐射冷却和热传导存在时热波和声波的分类和特性。除了Spitzer对平行热导率的表达式外，加热和冷却过程未作具体规定。此外，我们研究了在极短和极长波长的极端极限以及中间波长范围内等压和等容热模式的存在；我们解决了一个关于纯绝热扰动存在的常见误解。我们还对G.B. Field（1965）推导出的无限均匀流体介质的色散关系进行了深入分析。这使得能够生成增长率和色散图，为不同波长范围内的热不稳定性提供洞察。在加入热传导后，我们的研究对T.Waters和D.Proga（2019）之前概述的不稳定性区域进行了细化分类。我们的发现证实，当Field长度小于或与热波长相当时，他们的分类是成立的。对于更大的Field长度，简化分类变得不切实际。此外，我们讨论了灾难性冷却不稳定性（T.Waters和A.Stricklan 2025）在日冕降雨形成中的潜在影响。
英文摘要：
Thermal instability plays a crucial role in the dynamics of astrophysical plasmas. Building upon the foundational work of G. B. Field (1965) and the subsequent analysis by T. Waters & D. Proga (2019), this study revisits thermal instability in a uniform, non-magnetic medium. We aim to reevaluate and expand the understanding of instability domains, focusing on the classification and characteristics of thermal and acoustic modes in the presence of heating, radiative cooling, and thermal conduction. Except for Spitzer's expression for parallel thermal conductivity, heating and cooling processes are unspecified. Additionally, we investigate the existence of isobaric and isochoric thermal modes across the extreme limits of very short and very long wavelengths, as well as at intermediate wavelengths; we address a common misconception about the existence of purely adiabatic perturbations. We also perform an in-depth analysis of the dispersion relation for an infinite, uniform hydrodynamic medium, as derived by G. B. Field (1965). This enables the generation of growth rate and dispersion diagrams, providing insight into thermal instability across different wavelength ranges. With the inclusion of thermal conduction, our study refines the classification of the instability regions previously outlined by T. Waters & D. Proga (2019). Our findings confirm that their classification holds when the Field length is smaller than or comparable to the thermal wavelength. For larger Field lengths, a simplified classification becomes impractical. Furthermore, we discuss the potential implications of the catastrophic cooling instability (T. Waters & A. Stricklan 2025) in coronal rain formation.
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