Stochastic and discrete time models of long-range turbulent transport in the scrape-off layer

摘要

The two dimensional stochastic time model of scrape-off layer (SOL) turbulent transport is studied. The instability arisen in the system with respect to the stochastic perturbations of both either density or vorticity reveals itself in the strong outward bursts of particle density propagating ballistically across the SOL. The stability and possible stabilization of the cross-held turbulent system depend very much upon the reciprocal correlation time between density and vorticity fluctuations. The probability distribution function (pdf) of the particle flux for the large magnitudes of flux events can be modeled with a simple discrete time toy model of random walks concluding at a boundary. The spectra of wandering times feature the pdf of particle flux in the model and qualitatively reproduce the experimental statistics of transport events.