Simulation campaign of the turbulent diffusion at the edge of fusion devices

Abstract

The understanding of cross-field transport is crucial for optimizing the properties of magnetic confinement in fusion devices. In this work, a two-dimensional, simplified model is used to study the turbulent dynamics in the region of the scrape-off layer. The numerical model, based on the reduced Braginskii equations, is able to describe the formation and the evolution of blob-like structures. The dynamics has been investigated by using both classical Eulerian analysis and the Lagrangian approach, by varying the ambient conditions of the plasma. The major goals are (i) a detailed and systematic study of turbulence by varying the plasma jump conditions in the edge tokamaks plasmas and (ii) a Lagrangian diffusion study of the edge turbulence by using an appropriate Braginskii model. It has been found that both the magnetic shear and the plasma mean profiles of density and temperature are crucial for setting the properties of the transport. By following fluid tracers, diffusive transients for the radial transport are observed, at length scales larger than the typical blob size. This work is relevant for the comprehension of the turbulent transport at tokamaks edges.