Examination of ITER Central Solenoid prototype joints

The ITER Magnet System will be the largest and most challenging integrated superconducting magnet systemever built. For the Central Solenoid (CS), cable–in–conduit - conductors (CICCs) of nearly one kilometre lengthare produced, but still, it will be necessary to connect several lengths together to wind the gigantic 110 tonnescoils. The creation of these superconducting joints is one of the most delicate parts of the assembly. There arethree types of ITER CS joints: splice joints, coaxial joints and twin–box joints. US ITER, the ITER DomesticAgency of the USA produced a prototype containing all three types of joints. The goal is to test the performanceof the joints in the SULTAN facility of the Swiss Plasma Center (SPC), capable of reproducing close–to–serviceconditions: high magneticfield (up to 11 T backgroundfield), high current (up to 100 kA) and high massflowrate of supercritical helium for cooling. The paper describes the results of a comprehensive examination cam-paign aimed at understanding the relation between fabrication and performance of the CS prototype joints. Thetest campaign combines advanced image analysis for the assessment of the void fraction of the conductors withScanning Electron Microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) to evaluate the quality of the contact between the strands and the sleeve / sole of the joints.