Poloidal field coil and cryogenic systems for the TFCX tokamak

The Tokamak Fusion Core Experiment (TFCX) is considering four design options, each of which has superconducting poloidal field (PF) coils. AThe use of a superconducting PF system is a feature of three of the four the conceptual design options. The high performance copper TF option has a partially superconducting PF system. The TFCX PF system will be unique in scale and performance. No operating tokamak or tokamak under construction has a superconducting PF system. A unique feature of the TFCX PF system will be the combination of moderately high pulsed field loads and neutron/gamma loads, due to the light neutron shielding required for a cost-effective next step tokamak reactor. The reference concept for the superconductor in the TFCX PF coils is an internally-cooled, cabled superconductor (ICCS), similar to that used in the Westinghouse LCP and the M.I.T. 12 T Coils, but probably using a more advanced superconductor and conduit design. Three different cooling topologies are being investigated: conventional cable in conduit, cable and tube in conduit, and internally-cabled, externally-cooled construction. For the all superconducting tokamak options, all coils are contained in a common dewar. For the options with copper toroidal field magnets, most of the coils are contained by an inner dewar, while the large bore ring coils have separate dewars and cooling systems. Pulsed and steady-state cryogenic heat loads must be removed from the poloidal field coils and vacuum system cryopumps. A conventional helium refrigerator/liquefier is combined with a separate cold circulator loop for the forced-flow magnet windings.