A probabilistic transport model with two critical mechanisms for magnetically confined plasmas.

S. BOUZAT

Mar del Plata

Conferencia; XV Conference on Nonequilibrium Statistical Mechanics and Nonlinear Physics. Medyfinol’06.; 2006

Un.N de Mar del Plata, Un. de Los Andes (Chile), UBA.

A consistent description of transitions to improved confinementregimes in terms of a probabilistic transport model is presented.The model could be of relevance beyond the field of plasma physicsas a general transport model including two critical mechanismsacting respectively on the first and second spatial derivatives ofthe density. These mechanisms alow to switch between threedifferent transport channels: one corresponding to classicaldiffusion and the other two to different scale free transportmechanisms. The dependence of the transport properties on thesecond derivative models the appearance of a sheared radialelectric field, that causes a reduction of transport. The resultsof the model reproduce the enhancements of confinement time andthe appearance of fluctuations (associated to edge localizedmodes) that take place during transitions, when the fuelling rateis increased.