Turbulent transport regimes in the presence of an X-point magnetic configuration

Abstract

We analyze the transport properties of the two-dimensional electrostatic turbulence characterizing the edge of a Tokamak device from the study of test particles motion (passive fluid tracers) following the $E\times B$ drift. We perform statistical tests on the tracer population in order to assess both the magnitude and the main features of transport. The role of other physical properties, such as viscosity and inverse energy cascade in the spectrum, is also considered. We outline that large scale eddies are responsible for greater transport coefficients, while the presence of an X-point magnetic field reduces the mean free path of the particles, however generating a larger outliers population with respect to a Gaussian profile.