Analytical Approach To Predict The Particle Exhausts For Arbitrary Demo Divertor Configurations

The pumping efficiency, defined as the capability of neutral particles to be exhausted into the pumping system can be assessed analytically based on particle balance requirements valid for arbitrary divertor configurations and plasma performances of fusion reactor. It is shown that the pumping efficiency depends mainly on the ratio of the surface area bounding the divertor plenum from the SOL to the surface at the entrance to the pumping port, on the conductance of the pumping ports and the type of neutrals (atoms, molecules). By varying these parameters the pumping features of SN and SF divertor configurations is assessed. The analytical model can be used for checking the consistency of boundary conditions used in existing numerical codes such as DIVGAS with the necessity to pump out a required particle throughput at given conductance of the divertor port.