Bending Performance Analysis of a Compact Twisted Stacked YBCO Cable with Stepped Grooves

A novel stepped-groove structure for twisted stacked-tape cable (TSTC) is proposed to improve space utilization and bending performance. By laterally shifting the grooves of a conventional TSTC, additional tapes can be inserted adjacent to the original slots, allowing for a more compact arrangement. Electromagnetic simulations show that the proposed design enables a 23% increase in tape capacity and achieves 17%–22% higher critical current under both self-field and 10 T external field conditions. To experimentally validate the design, a three-groove prototype cable is fabricated and tested in both straight and bent configurations, with a minimum bending diameter of 220 mm. The straight-sample test results agree well with the electromagnetic model. A 3D mechanical model is developed to simulate the degradation behavior under twisting and bending, and the results matched experimental data, confirming the reliability of the modeling approach. Parametric studies based on the mechanical model further investigated the influence of twist pitch and groove geometry, revealing performance saturation trends. Compared to a traditional straight-groove TSTC, the tapes in the deep groove of the stepped structure exhibit more stable current retention under tight bending, indicating its strong engineering adaptability and potential for use in compact, high-field superconducting magnets.