SOLPS 5.0 simulations of the high-field side divertor detachment of L-mode plasmas in ASDEX upgrade with convection-dominated radial SOL transport

Abstract

SOLPS 5.0 simulations assuming convection-dominated radial ion transport show qualitative and quantitative agreement with measurements of detached high-field side (HFS) divertor conditions for unseeded low-power L-mode plasmas in ASDEX Upgrade, while simultaneously maintaining a reasonable match to the density and temperature measurements at the low-field side (LFS) and HFS midplanes within the scatter of the data. The decreased diffusive transport from the high-density region in the HFS divertor volume across the separatrix into the core enables spatial extension of the high-density front to above the X-point in agreement with spectroscopic measurements. The suppressed ion fuelling from this region into the core plasma allows increasing the neutral D2 fuelling to experimental levels, leading to agreement with the measured sub-divertor neutral fluxes within 30%. Detachment of the HFS divertor is observed as a significant decrease of the target ion flux and as reproduction of the characteristic roll-over behaviour of the integrated target ion current at increasing upstream density.