The Operation Test of YBCO Binary Current Leads Developed for an NI REBCO Magnet

This paper presents the operation test results of a new type of YBCO binary current leads with a cryostat designed for a no-insulation (NI) REBCO magnet at Wuhan National High Magnetic Field Center (WHMFC). Multi-physical signals including current, voltage, temperature, pressure, and liquid helium level from leads and liquid helium cryostat are recorded through data acquisition software developed by Labview. The operation test is composed of cooling, vaporizing, and charging processes. The test results have been introduced and analyzed, which show that the YBCO tapes of the binary leads can enter into the fully superconducting state under vapor-cooled mode and possess an adequate temperature margin. The reasonable liquid helium boil-off rate indicates that the heat leakage from the leads and cryostat is within an acceptable range, guaranteeing ample time for the magnet's operation with the YBCO binary leads and cryostat system. The measured results are compared with the predictive simulation model. The heat load and transient characteristics of temperature and voltage signals are discussed.