Design of the ITER torus prototype cryopump

Forschungszentrum Karlsruhe (FZK) is developing the ITER prototype torus exhaust pumping system, comprising eight identical cryosorption pumps to provide a high pumping speed and capacity, and fast regeneration. The prototype pump features an integral inlet valve with a nominal diameter of 800 mm which can be closed during the plasma pulse operation for on-line regeneration. The pump design is incorporating the results of the experimental campaigns performed with the model torus cryopump in the TIMO test bed at FZK as well as the results achieved in the large scale tritium testing of an ITER relevant cryosorption pump set-up at JET. This paper summarizes the requirements for the pumping system and outlines how these are successfully met. The way in which the nominal parameters for the detailed design of the cryopumps are derived from the overall system specification is described. Finally, the detailed design of the pump and its sub-assemblies will be presented.