Cryogenic needs for future tokamaks

The ITER tokamak is a machine using superconducting magnets. The windings of these magnets well be subjected to high heat loads resulting from a combination of nuclear energy absorption and AC-losses. It is estimated that about 100 kW at 4.5 K are needed. The total cooling mass flow rate will be around 10 - 15 kg/s. In addition to the large cryogenic power required for the superconducting magnets cryogenic power is also needed for refrigerated radiation shield, various cryopumps, fuel processing and test beds. A general description of the overall layout and the envisaged refrigerator cycle, necessary cold pumps and ancillary equipment is given. The basic cryogenic layout for the ITER tokamak design, as developed during the conceptual design phase, and a short overview about existing tokamak designs using superconducting magnets is given. (Author)