Correlations and Kappa Distributions: Numerical Experiment and Physical Understanding.

IF 2.1 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY
Entropy Pub Date : 2025-03-31 DOI:10.3390/e27040375
David J McComas, George Livadiotis, Nicholas V Sarlis
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Abstract

Kappa distributions, their statistical framework, and their thermodynamic origin describe systems with correlations among their particle energies, residing in stationary states out of classical thermal equilibrium/space plasmas, from solar wind to the outer heliosphere, are such systems. We show how correlations from long-range interactions compete with collisions to define the specific shape of particle velocity distributions, using a simple numerical experiment with collisions and a variable amount of correlation among the particles. When the correlations are turned off, collisions drive any initial distribution to evolve toward equilibrium and a Maxwell-Boltzmann (MB) distribution. However, when some correlation is introduced, the distribution evolves toward a different stationary state defined by a kappa distribution with some finite value of the thermodynamic kappa κ (where κ→∞ corresponds to a MB distribution). Furthermore, the stronger the correlations, the lower the κ value. This simple numerical experiment illuminates the role of correlations in forming stationary state particle distributions, which are described by kappa distributions, as well as the physical interpretation of correlations from long-range interactions and how they are related to the thermodynamic kappa.

相关性和Kappa分布:数值实验和物理理解。
Kappa分布、它们的统计框架和它们的热力学起源描述了它们的粒子能量之间的相关性,这些系统存在于经典热平衡/空间等离子体之外的静止状态,从太阳风到外日球层,都是这样的系统。我们展示了远程相互作用的相关性如何与碰撞竞争,以定义粒子速度分布的特定形状,使用一个简单的碰撞数值实验和粒子之间可变的相关性。当相关性被关闭时,碰撞驱动任何初始分布向平衡和麦克斯韦-玻尔兹曼(MB)分布演化。然而,当引入某种相关性时,分布演变为由kappa分布定义的不同的稳态,该分布具有热力学kappa κ的某个有限值(其中κ→∞对应于MB分布)。此外,相关性越强,κ值越低。这个简单的数值实验阐明了相关性在形成由kappa分布描述的稳态粒子分布中的作用,以及远程相互作用中相关性的物理解释以及它们与热力学kappa的关系。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Entropy
Entropy PHYSICS, MULTIDISCIPLINARY-
CiteScore
4.90
自引率
11.10%
发文量
1580
审稿时长
21.05 days
期刊介绍: Entropy (ISSN 1099-4300), an international and interdisciplinary journal of entropy and information studies, publishes reviews, regular research papers and short notes. Our aim is to encourage scientists to publish as much as possible their theoretical and experimental details. There is no restriction on the length of the papers. If there are computation and the experiment, the details must be provided so that the results can be reproduced.
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