UEDGE and DEGAS modeling of the DIII-D scrape-off layer plasma

Abstract

This paper presents work to develop benchmarked theoretical models of scrape-off-layer (SOL) characteristics in diverted tokamaks by comparing shot simulations, using the UEDGE plasma fluid and DEGAS neutral transport codes, to measurements of the DIII-D SOL plasma. The experimental data include the radial profiles of n e, T e, and T i, the divertor exhaust power, the intensity of H α emission, and profiles of the radiated power. A very simple model of the anomalous perpendicular transport rates produces consistency between the calculated and measured radial profiles of the divertor power, and of the midplane densities and temperatures. Experimentally, the measured exhaust power is now 80–90% of the input power. The simulated peak power on the outer leg of the divertor floor is now within 20% of the measured power. Various sensitivies of these comparisons to model assumptions are described. Finally, these benchmarked models have been used to examine the effects of various baffle configurations for the radiative divertor upgrade in DIII-D.