Heat deposition in the ITER FEAT poloidal field coils during a plasma scenario

During the last phase of the EDA (Engineering Design Activities) of the ITER (International Thermonuclear Experimental Reactor) project, a fully superconducting PF (Poloidal Field) system has been designed to cope with the requirements of the FEAT (Fusion Energy Advanced Tokamak) version of ITER: providing the magnetic field required to develop, shape and control the 15 MA plasma during the 900 s of a typical plasma scenario. The CS (Central Solenoid), divided into 6 Nb₃Sn subcoils, and the six outer NbTi PF coils will experience severe heat loads especially during the 400 s of the plasma burn: nuclear heating due to the 400 MW of fusion power, thermal radiation, and ac losses (30 to 300 kJ in the PF coils). The ac losses along the PF coil pancakes are deduced from accurate magnetic field computations performed by the TRAPS code (analytical integration of the Biot-Savart law over the cross section of 3-D current elements). Using as input these heat loads, including thermal radiation and nuclear heating, a thermal-hydraulic analysis of the PF coil cable-in-conduit conductor is performed with a finite element code, GANDALF: the temperature increases (0.1 to 0.3 K) are computed, the temperature margins of the conductor are thus evaluated.