Operation Space of Divertor detachment in DEMO

In the paper we consider the operation window of DEMO divertor detachment expected under DEMO I operation conditions for various external impurity levels, particle throughput and pumping conditions, envisaged for fusion reactor. The operation region is defined in terms of upstream heat flux and the upstream density and is bounded by the burn conditions and by the transition threshold between L and H mode. It is also restricted by the density and upstream heat fluxes required for detach operation in DEMO divertor. The transition from the attached to the detached state is simulated in the frame of a simple model which includes the pumping efficiency dependence on density, recombination at the divertor plate and particle throughput. The model was benchmarked with JET experiment and reproduced global features of the transition. The neutral pressure in the divertor chamber and the particle flux to the cryo-and diffusion pump are estimated for detached divertor conditions as well as the number of required pumps.