When can Fokker-Planck Equation describe anomalous or chaotic transport?
Abstract
Description
The Fokker-Planck Equation, applied to transport processes in fusion plasmas, can model several anomalous features, including uphill transport, scaling of confinement time with system size, and convective propagation of externally induced perturbations. It can be justified for generic particle transport provided that there is enough randomness in the Hamiltonian describing the dynamics. Then, except for 1 degree-of-freedom, the two transport coefficients are largely independent. Depending on the statistics of interest, the same dynamical system may be found diffusive or dominated by its Lévy flights.
4 pages. Accepted in Physical Review Letters. V2: only some minor changes
4 pages. Accepted in Physical Review Letters. V2: only some minor changes