Stochastic modeling of MHD turbulence in magnetized plasma

• Modeling turbulent magneto-fluid dynamics by stochastic flow as a mapping.
• Sticky motion decreases with increasing perturbation leading to normal diffusion.
• Temporary trapping of field lines in the main islands of the turbulence.
• Strong or irregular field suppresses diffusion escape.
• Anomalous diffusion up to some crossover time, beyond which the diffusion is Gaussian.

This paper concerns the magneto-fluid dynamics modeled by the stochastic flow where the turbulent term is driven by the random forcing. Magnetohydrodynamic (MHD) turbulence can be interpreted in terms of a standard map (SM), modeling perturbed Hamiltonian systems, to explain some of the features of the problem. The dynamics generated by SM, although being chaotic, are influenced by periodic islands embedded in the chaotic sea due to stickiness effect and also to the behavior of the diffusion coefficient. Anomalous diffusion exists only up to some crossover time, beyond which the diffusion is Gaussian consistent with quasi-linear predictions. The results can be applicable to systems where there exist intensive interaction between a stochastic turbulent system and waves.