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Non-diffusive transport in plasma turbulence: a fractional diffusion approach

D. del-Castillo-Negrete·B. A. Carreras·V. E. Lynch
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Abstract

Numerical evidence of non-diffusive transport in three-dimensional, resistive pressure-gradient-driven plasma turbulence is presented. It is shown that the probability density function (pdf) of test particles' radial displacements is strongly non-Gaussian and exhibits algebraic decaying tails. To model these results we propose a macroscopic transport model for the pdf based on the use of fractional derivatives in space and time, that incorporate in a unified way space-time non-locality (non-Fickian transport), non-Gaussianity, and non-diffusive scaling. The fractional diffusion model reproduces the shape, and space-time scaling of the non-Gaussian pdf of turbulent transport calculations. The model also reproduces the observed super-diffusive scaling.

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D. del-Castillo-Negrete, B. A. Carreras, V. E. Lynch. 2004-03-04. Non-diffusive transport in plasma turbulence: a fractional diffusion approach. https://doi.org/10.1103/physrevlett.94.065003

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