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Description
High-temperature superconducting (HTS) coils are widely utilized in magnet applications due to their superior performance in compactness and energy efficiency. Traditionally, the critical current (Ic) of HTS coils has been measured using the 100 μV/m criterion, adopted from the international standard for second-generation HTS wires. However, as discussed in previous research, this criterion may not be suitable for determining the critical current of HTS coils due to the non-uniform magnetic field distribution within the coil.
The authors investigate the impact of applying different critical current measurement criteria on the performance degradation of HTS coils under conduction cooling conditions using a Gifford-McMahon (G-M) cryocooler and vacuum insulation. The criterion previously proposed by the authors, which addresses the limitations of the 100 μV/m standard, is employed as the minimum threshold, while the conventional 100 μV/m criterion is used as the maximum threshold. Critical current measurements are conducted under different criteria to evaluate whether repeated testing leads to irreversible performance degradation in HTS coils.
By applying conduction cooling using a cryocooler instead of conventional liquid nitrogen cooling, this research enables critical current measurements across various temperature ranges, providing a more practical assessment of HTS coil performance in real-world applications. The findings are expected to offer insights into effective criteria for critical current measurements, helping to prevent coil damage and improve the durability and operational safety of HTS coils during repeated measurements.
