Factory Acceptance Test of 50-kA HTS Current Leads for the ITER CS Magnet Test Application

The Institute of Plasma Physics, Chinese Academy of Sciences was contracted by General Atomics Company to develop a superconducting feeder system containing a pair of 50-kA high-temperature superconducting (HTS) current leads for ITER central solenoid magnet test. These HTS current leads (HTSCL) are based on the previous ITER lead design experiences. However, the vertical assembly design of HTSCL which is different from ITER's horizontal assembly causes the water leakage in the insulation flange during the initial phase. Some improvements were recognized and expected to avoid the potential risk for further prototypes and series production of ITER leads. Some development experiences are shared in this paper. The HTS current leads contain BiSCCO AgAu matrix tapes to minimize the heat load to 4.5 K end. Its resistive part is cooled by 50-K helium. In the HTS part, the conduction cooling is adopted. The HTS current leads were integrated in the feeder system to perform 4.5-K full current test. The factory acceptance test was implemented to verify the high-voltage and thermodynamic performances. The maximum current of 55 kA was achieved. The test indicates that the helium mass flow consumption is 3.3 g/s per lead and the loss of flow accident time is approximate to 10 min at the nominal current with the stoppage of 50-K helium. The insulation flange passed the high-voltage test of 15 kV, while the leakage current is less than 1 mA after the improvement. More detailed test results will be shown in this paper.