Experiment of joints resistance and critical current of Bi2212 conductor

Bi2Sr2CaCu2Ox is a potential material for the superconducting magnets of the next generation of Fusion reactors. A R&D activity based on Bi2212 wire is running at ASIPP for the feasibility demonstration of CICC. One sub-size conductor cabled with 42 wires was designed and manufactured. A test facility was designed and set-up to measure the resistance of joints and the critical current of the Bi2212 CICC in liquid helium. A superconducting transformer, which consisted of two concentric layer-wound superconducting solenoids, was used to provide the current of the conductor sample. Both of the primary and secondary coils were immersed in liquid helium during the experiments. The highest current of the secondary loop was up to around 14 kA. The critical current of the conductor was 13.2 kA with criterion of 1 μV/cm and the joints resistances were lower than 50 nΩ.