1. The operational window for divertor detachment in a fusion reactor – A physics-technology integrated approach
FIP/P7-12
Background: The reactor throughput and particle composition together with the requirements of the pressure or density at which this throughput has to be pumped define the design of the vacuum system. The detachment conditions define the gas throughput.
This paper shows how this is linked for two candidate DEMO pump configurations (ITER type cryo or novel diffusion pumps).
The combined case
The detachment problem
5 cryo or 15 diffusion pumps are required for removal of different particle fluxes The operational points are indicated by circles.
The pumping problem
Neutral density in the divertor region vs particle flux density to the plate; at given particle flux the neutral density required to pump is somewhat less in the cryopump case compared to the diffusion pump case.
Heat flux density along B and particle flux of the plate as a function of Ar impurity concentration for a given total number of particles (average edge density, 1∙1021/m³); transition occurs at an Ar concentration of ~0.85% and a given upstream plasma density 0.35∙1020/m³.
Operation space of divertor detachment in terms of heat flux to divertor and upstream (separatrix) density for various Ar impurity levels.
Christian Day, Y. Igitkhanov, V. Hauer – FEC 2014 – Saint Petersburg, RUS, Oct 2014