Defect Detection in Superconducting CICC Joints by Means of Magnetic Field Measurements

To reduce the manufacturing risks, some of the largest superconducting Nb₃Sn magnets for fusion applications will be made of smaller coils, individually heat treated and impregnated, then permanently connected by resistive joints. These joints and the magnet terminations shall be very reliable and shall not deliver excessive thermal load to the cooling He. A non destructive test procedure, based on magnetic field measurements, may be very helpful to assess the joints and terminations quality. Starting from a realistic termination geometry, the paper shows the results of a numerical model of possible magnetic measurements sensitive to a set of termination defects.