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arXiv 0904.3610nlin.CD
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各向异性磁场turbulence中磁力线扩散的Kolmogorov-Sinai熵

Kolmogorov-Sinai entropy in field line diffusion by anisotropic magnetic turbulence

Alexander V. Milovanov, Rehab Bitane, Gaetano Zimbardo

摘要:

在数值模拟模型和理论研究的基础上,分析了磁力线湍流扩散中的Kolmogorov-Sinai(KS)熵。在强各向异性磁湍流的参数范围内,KS熵与早先预测的标度关系[Rev. Mod. Phys. { \bf 64},961(1992)]有很大的偏差。特别地,发现了相对于所谓的久保数$R\gg 1$($R = (δB / B_0) (ξ_\| / ξ_\bot)$,其中$δB / B_0$是均方根磁波动场与磁场强度的比率,并且$ξ_\bot$和$ξ_\|$是各个维度中的相关长度)的减慢的对数行为,而不是幂律依赖性。这些差异从哈密顿动力学的一般原理解释。我们讨论了在管理的范式“渗流”运输,其特征在于$R\to\infty$,关联它与伪混沌(随机非混沌动力学与零李雅普诺夫指数)的概念的哈密顿性质的含义。这项研究的应用涉及聚变和天体物理等离子体,并通过数学类比等离子体物理学以外的问题。这篇研究文章是为了纪念乔治M。扎斯拉夫斯基

英文摘要:

The Kolmogorov-Sinai (KS) entropy in turbulent diffusion of magnetic field lines is analyzed on the basis of a numerical simulation model and theoretical investigations. In the parameter range of strongly anisotropic magnetic turbulence the KS entropy is shown to deviate considerably from the earlier predicted scaling relations [Rev. Mod. Phys. {\bf 64}, 961 (1992)]. In particular, a slowing down logarithmic behavior versus the so-called Kubo number $R\gg 1$ ($R = (δB / B_0) (ξ_\| / ξ_\bot)$, where $δB / B_0$ is the ratio of the rms magnetic fluctuation field to the magnetic field strength, and $ξ_\bot$ and $ξ_\|$ are the correlation lengths in respective dimensions) is found instead of a power-law dependence. These discrepancies are explained from general principles of Hamiltonian dynamics. We discuss the implication of Hamiltonian properties in governing the paradigmatic "percolation" transport, characterized by $R\to\infty$, associating it with the concept of pseudochaos (random non-chaotic dynamics with zero Lyapunov exponents). Applications of this study pertain to both fusion and astrophysical plasma and by mathematical analogy to problems outside the plasma physics. This research article is dedicated to the memory of Professor George M. Zaslavsky

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