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The Divertor Tokamak Test (DTT) facility [1], under construction in Frascati, Italy, will rely on a fully-superconductive magnetic system. Thanks to the limited dimension of the machine, three cryo-lines will house all the Feeders for the Central Solenoid (CS), for the Toroidal Field (TF) and for the Poloidal Field (PF) coils, respectively. The in-cryostat route of the different Feeders (two for any of the 6 CS and PF coils, and 6 in total for the 18 TF coils, interconnected through 3 SC jumpers) will be up to ~ 10m each. The Feeders, designed with twisted NbTi and Copper strands in a Cable-In-Conduit Conductor (CICC) layout (with or w/out the central cooling channel for the different types of coils) with a square jacket, will be cooled by a dedicated line of Supercritical Helium at 0.6 MPa and 4.5 K at the inlet. In view of the different plasma scenarios foreseen for the DTT operation, it is important to verify that the thermal-hydraulic performance of the Feeders, subject in operation to AC losses, joule heating from the resistive joints located at the terminations, and parasitic load by radiation from the thermal shield at 80 K and by conduction from the clamping, does not pose any issues to the machine operation. The minimum temperature margin, computed for the different conductors in the most demanding plasma scenarios, is presented and discussed in this paper, showing the conservativeness of the design for such components.
[1] R. Martone, R. Albanese, F. Crisanti, A. Pizzuto, P. Martin. “ “DTT Divertor Tokamak Test facility Interim Design Report, ENEA (ISBN 978-88-8286-378-4), April 2019 ("Green Book")” https://www.dtt-dms.enea.it/share/s/avvglhVQT2aSkSgV9vuEtw
