AC loss measurement of 46 kA-13T Nb3Sn conductor for ITER

AC Losses of Nb3Sn conductor samples with various void fractions for the IT ER Central Solenoid Model Coil (CSMC) were measured by using calorimetric a nd magnetization techniques. The CSMC is designed to generate the magnetic field of 13 T at the operating current of 46 kA, The conductor consists of the multi-stage cable, having 1152 Nb3Sn strands, and Incoloy 908 square ja cket with circular hole. The strands are coated by chrome plating with 2 mu m layer, The last sub-cables are wrapped with Inconel tape, having high ele ctric resistivity, to reduce the coupling current loss. The optimum void fr action for pulse coils is obtained from the relation between the coupling t ime constant and the void fraction. It is indicated that the sub-cable wrap ping is very effective in limiting the coupling current between the sub-cab les, as expected. The AC losses of the CS insert were measured in various o perating modes. From these obtained results, the validity of conductor desi gn is demonstrated.