Performance Improvement by Upgrading of the Multi-Field Test Facility of Superconducting Wires/Tapes

A versatile test facility capable of providing cryogenic-electro-magnetic multifield was constructed for field-dependent and mechanical property measurements of superconducting wires/tapes at Lanzhou University of China. It firstly realized a continuous variation of cryogenic temperature from 4.2 K to 77 K (~5 K/min) and a transport current from 0-1000 A (~1 A/min) in a background magnetic field of 3.5 T. Aiming at improvements of samples in a larger scope, the facility was upgraded on several sub-systems, for example, the background superconducting magnet, variable-temperature cryogenic and mechanical loading and control system. This paper presents the latest upgrading of the multifield test facility. A semi-open split NbTi magnet with a combined cooling system was newly fabricated to generate a transverse background filed up to 5 T in a relatively larger test space of Ø100 mm × H800 mm. To improve the cryogenic system for refrigeration, a compact cryostat of cylinder-like vacuum Dewar vessel with a visible window, cooled by a Gifford-McMahon (GM) cryocoolers, was constructed. The continuous temperature variations from 4 to 353 K (~10 K/min) and a high transport current application 0-1000 A (~3 A/min) for testing superconducting wires/tapes were achieved. Additionally, a data acquisition system with accurate and synchronous measurements of multifield including current, temperature, strain, and AC losses was enhanced. Some tests illustrated that the upgrading of sub-systems and extend of operation range for the test facility were well improved. It will contribute to the progress in understanding design issues for superconducting wires/tapes under intense multiple fields.