Simulation of edge-plasma profiles and turbulence related to L-H transitions in tokamaks

Results are presented for fluid-equation simulations of transport and turbulence in the edge region of a tokamak using the transport code UEDGE and the turbulence code BOUT. UEDGE calculates two-dimensional plasma and neutral gas profiles using empirical radial transport coefficients, while BOUT simulates three-dimensional plasma turbulence and resulting transport using experimental or UEDGE plasma profiles. Using UEDGE, the radial electric field structure near the magnetic separatrix is studied for variations of core power, anomalous perpendicular ion viscosity, νaperpendicular, and prompt ion loss. A BOUT simulation measures the effective νaperpendicular from the calculated turbulence-induced radial ion current, giving a value similar to the ion heat diffusivity. (author)