Heat Treatment of Two-Turn Nb 3 Sn Superconducting Coil

A heat treatment system was built at High Magnetic Field Laboratory, Chinese Academy of Sciences (CHMFL) for the heat treatment of large-scale Nb 3 Sn superconducting coils and conductors. In order to evaluate the manufacturing technique of the joints for the Nb 3 Sn CICC, a two-turn Nb 3 Sn superconducting coil with two superconducting joints had been developed. A two-turn coil together with several Nb 3 Sn witness samples was heat-treated. Experimental and finite elemental analysis was also discussed. The results of the measurements met the requirements of the magnet design.