B2-EIRENE modelling of He compression and enrichment

Helium compression and helium enrichment are important for most future fusion reactors since the He ash produced by the nuclear reactions needs to be pumped out to prevent its accumulation in the core of the plasma. (Helium compression is the ratio of the helium density in the pumping plenum to the helium density in the plasma; helium enrichment is the ratio of the helium compression to the hydrogen or deuterium compression.) In this work the B2-EIRENE code is used to model helium compression and enrichment on ASDEX Upgrade with divertor II under a variety of plasma densities, input powers, transport coefficients and divertor geometries so as to determine the range of acceptable operating conditions for effective He removal. A broad range of acceptable plasma conditions is found, though a lower limit of the upstream separatrix density is noted