Spiegazione microscopica del limite di densita` nei Tokamak: aspetti fondamentali dell'interazione radiazione Materia

by Luigi Galgani (Università di Milano 1)

Thursday 25 Mar 2010, 17:00 → 18:00 Europe/Rome

Aula Conversi (Dipartimento di Fisica - Ed. G.Marconi)

A microscopic deduction of the density limit for tokamaks: fundamental aspects of the many-body matter-radiation interaction. Fusion research on magnetic confinement is confronted with a severe problem concerning the electron densities to be used in fusion devices. Indeed, high densities are mandatory for obtaining large efficiencies, whereas it is empirically found that catastrophic disruptive events occur for densities exceeding a maximal one. On the other hand, despite the large theoretical work “there is no widely accepted, first principles model for the density limit”. Here, we show that the existence of a density limit is a general collective feature of the many-body electrodynamics of point particles, which is lost in the continuum approximation. For a simple microscopic model of a magnetized plasma suited for a tokamak, with no free parameters, we give a density limit which turns out to fit rather well the data.