Modeling of argon seeding in ASDEX Upgrade H-mode plasma with SOLPS5.0

Abstract

SOLPS modeling of Ar seeding in ASDEX Upgrade H-mode plasma shows that the divertor compression of Ar increases with the seeding rate when the inner divertor is detached and the outer divertor is attached. This results from the redistribution of the Ar density as the inner divertor detaches. During the detachment of the inner divertor, the parallel friction and thermal forces on Ar increase in the inner divertor and decrease in the outer divertor. The net force of the two directs Ar from the low field side to the high field side of the plasma along the field line. The net force is found to be stronger after the detachment of the inner divertor in the simulation. Although the divertor compression of Ar increases, the ratio of radiated power by Ar inside the divertor over that inside the separatrix does not increase after the detachment. This is because the radiation efficiency, i.e. the radiated per Ar particle on average decreases with the seeding rate in the divertor and increases inside the separatrix. The radiation efficiency in the simulation is determined by the characteristic cooling curve of Ar and the transport effects.