Interchange Instability Turbulence Model in Edge Tokamak Plasma

Interchange instability is investigated as a plausible mechanism to drive turbulence in the tokamak scrape‐off‐layer. By averaging density and electrostatic potential fluid equations along field lines, a reduced two dimensional model is obtained. Similarly to Rayleigh‐Bénard convection, interchange instability shows a instability threshold and presents localised modes (with a simple geometry and boundary conditions). The nonlinear, turbulent, behaviour of the model is investigated using numerical simulations. Preliminary results show a self‐organization of the flow in coherent structures with a departure from gaussian statistics.