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

Alexander V Milovanov, Rehab Bitane, Gaetano Zimbardo

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Abstract

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 (1992 Rev. Mod. Phys. 64 961). In particular, a slowing down logarithmic behavior versus the so-called Kubo number R ≫ 1 (R = (δB/B0) (ξ∥/ξ⊥), where δB/B0is the ratio of the rms magnetic fluctuation field to the magnetic field strength, and ξ∥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 → ∞, 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. © 2009 IOP Publishing Ltd.
Original languageEnglish
Article number075003
Pages (from-to)-
JournalPlasma Physics and Controlled Fusion
Volume51
Issue number7
DOIs
Publication statusPublished - 2009
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

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