Self-consistent cross-field transport model for core and edge plasma transport

A two-equation model to self-consistently determine cross-field fluxes in the edge and scrape-off layer (SOL) region of diverted plasma is used to complete 2D mean-field edge transport description of plasma wall interaction. Inspired by the Reynolds average Navier–Stokes simulations for neutral fluids, this model is based on the local evolution of the turbulent kinetic energy κ and its dissipation rate ɛ. These two equations are algebraically derived for RANS modeling and are very slightly modified and adapted to describe self-consistent plasma turbulent transport. The general features of the model are discussed and bridged to the well-known predator–prey and quasilinear models commonly used to investigate plasma transport. Specific closures are proposed based on the interchange turbulence. Results of the 1D model are confronted to experimental evidence by analyzing the computed SOL width and comparing the results to the existing scaling law for L-mode plasmas. Introducing a dependence on the shear of large scale flows, typically the zonal flows, 1D simulations can exhibit an H-mode like transition when increasing the input power, generating an increased stored energy thanks to an interface barrier located at the separatrix. Further 2D plasma–wall interaction simulations for WEST are analyzed that show a good match with the experimental profiles, as well as a ballooned transport driving turbulent transport in the divertor SOL and nearly no transport in the private flux region. The SOL width of WEST is also recovered. These results show the remarkable capability of the κ–ɛ model to capture key aspects of the physics of turbulent transport throughout the plasma knowing that a unique scalar free parameter is available to tune cross field transport in the whole 2D cross section of the plasma.