Simulation of plasma fluxes to material surfaces with self-consistent edge turbulence and transport for tokamaks

The edge-plasma profiles and fluxes to the divertor and walls of a tokamak with a magnetic X-point are simulated by coupling a 2D transport code (UEDGE) and a 3D turbulence code (BOUT). A relaxed iterative coupling scheme is used where each code is run on its characteristic time scale, resulting in a statistical steady state. Plasma variables of density, parallel velocity, and separate ion and electron temperatures are included, together with a fluid neutral model for recycling neutrals at material surfaces. Results for the DIII-D tokamak parameters show that the turbulence is preferentially excited in the outer radial region of the edge where magnetic curvature is destabilizing, yielding substantial plasma particle flux to the main chamber walls. The coupled transport/turbulence simulation technique provides a strategy to achieve physics-based predictions for future device performance.