Test results of the DTT poloidal field conductor samples in SULTAN: DC and AC characterization

The poloidal field (PF) magnet system of the Divertor Tokamak Test (DTT) facility consists of 6 superconducting coils with full top-down symmetry, realized in Nb3Sn (PF1 and PF6) and NbTi (PF2, PF3, PF4 and PF5). To validate the NbTi PF coil design, short samples of the cable-in-conduit-conductor cables (CICCs) have been qualified by dedicated cryogenic tests in the SULTAN facility at Swiss Plasma Centre (SPC, EPFL). In this work, we present the results of the two test campaigns conducted in August and September 2022, for the PF2/5 and PF3/4, respectively. The extensive characterization of the NbTi PF samples included a set of AC loss measurements using bipolar sinusoidal pulsing, as well as a set of DC tests spanning the range of the coils operability to assess the critical current, Ic, and the current sharing temperature, Tcs. The performances have been checked after electro-magnetic (EM) cyclic loading (up to 1000 cycles) at different B/I loads. The minimum quench energy (MQE) has also been measured at different temperatures. All tests confirmed the effectiveness of the PF CICCs design, showing good performance above the minimum acceptance values even at currents 110% higher than the nominal value.