Development and Experiment of HTS Magnet With Composite Superconducting Cable

In the future, large-capacity SMES system is expected to play an important role in power grids, where magnet is a key component. The single tape current capacity is difficult to meet operating requirements of large-scale magnets in engineering application. Considering the magnet economic cost, it is not suitable to increase the capacity by increasing the amount of superconducting tapes and reducing the operating temperature. It is necessary to use composite superconducting conductors to increase the current carrying capacity for large-scale magnets application. This paper describes the structure and preparation process of a twisted stacked-tape in tube (TSTT) composite cable with an inner cooling channel. Then a pancake coil was fabricated using a 100-metre TSTT composite cable, and the pancake coil was cooled by liquid nitrogen immersion, with inner liquid nitrogen forced flow cooling environment. The critical current and strain of the pancake coil were measured at 77 K. With the criterion of 1 μV/cm, the critical current was 650 A at 77 K. The trend and magnitude of strain in key components are generally consistent. The experimental results verify the rationality of the design of this TSTT composite cable and provide a valuable reference for large-scale magnet design.