Bending performance analysis on YBCO cable with high flexibility

Abstract

In order to utilize high-temperature superconducting Yttrium Barium Copper Oxide (YBCO) tapes to develop superconducting cables for high magnet field applications, it is critical to ensure the stable operation of the YBCO cable under challenging mechanical and thermal conditions. A new type of cable featuring the winding of YBCO and copper tapes around a spiral stainless steel tube has been proposed to increase flexibility and cooling. Experiments are performed to confirm that its critical current varies with the bending diameter. The cables wound with nine YBCO tapes in three layers show a critical current degradation of less than 5% for a bending diameter of 30 mm. The performance of the cable degrades as the number of wound layers increases. The critical current degradation of cable specimens wound from 15 tapes in five layers reached approximately 12% for a bending diameter of 30 mm. In addition, when compared to traditional CORC cable specimens, the developed cable specimens show better-bending flexibility and achieve a lower critical bending diameter. The finite element models show that the higher elasticity coefficient and lower plasticity of the stainless steel spiral tube results in a lower strain on the YBCO tapes of the HFRC cable than that of the CORC cable, and the maximum strain on the YBCO tapes of the HFRC cable was only about 10% of that of the CORC cable. Therefore, it is less likely that the YBCO tape in this type of cable will reach the irreversible strain limit during bending, resulting in a degradation in current carrying performance. Furthermore, the cooling efficiency can be improved by flowing the cooling medium inside the central core, which can significantly improve its thermal stability. These advantages indicate the possibility of using it in future high-field magnets with high current carrying capacity at fields greater than 15 T.