  We discuss a stochastic model for the behavior of electrons in a magnetically
confined plasma having axial symmetry. The aim of the work is to provide an
explanation for the density limit observed in the Frascati Tokamak Upgrade
machine. The dynamical framework deals with an electron embedded in a
stationary and uniform magnetic field and affected by an orthogonal random
electric field. The behavior of the average plasma profile is determined by the
appropriate Fokker-Planck equation associated to the considered model and the
disruptive effects of the stochastic electric field is shown. The comparison
between the addressed model and the experimental data allows to fix the
relevant spatial scale of such a stochastic field. It is found to be of the
order of the Tokamak micro-physics scale, i.e. few millimeters. Moreover, it is
clarified how the diffusion process outlines a dependence on the magnetic field
as $\sim B^{-3/2}$.
