48,055 research outputs found
Poisson-Vlasov : Stochastic representation and numerical codes
A stochastic representation for the solutions of the Poisson-Vlasov equation,
with several charged species, is obtained. The representation involves both an
exponential and a branching process and it provides an intuitive
characterization of the nature of the solutions and its fluctuations. Here, the
stochastic representation is also proposed as a tool for the numerical
evaluation of the solutionsComment: 17 pages, 5 figure
Stochastic and Discrete Time Models of Long-Range Turbulent Transport in the Scrape-Off Layer
Two dimensional stochastic time model of scrape-off layer (SOL) turbulent
transport is studied. 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- field turbulent
system depend very much upon the reciprocal correlation time between density
and vorticity fluctuations. Pdf of the particle flux for the large magnitudes
of flux events can be modelled 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.Comment: 21 pages,11 figure
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