A 6-around-1 cable using high-temperature superconducting STAR ? wires for magnet applications

To generate a dipole field above 20 T, we need high-temperature superconductors, including REBa2Cu3O7-x (RE = rare earth, rebco) coated conductors. However, the optimal architecture of a high-current flexible rebco cable is not yet settled for high-field magnet applications. Here we report a 6-around-1 cable concept based on the high-temperature superconducting star (R) wires. We made two cable samples. One had a single star (R) wire and the other had six star (R) wires. The cable with six star (R) wires was 1.5 m long. It had a diameter of 5.7 mm and a pitch length of 52 mm. The critical current of the cable before bending was 1448 A at 77 K, retaining at least 77% of the total critical current from individual star (R) wires. The cable had a low n value around 4.5. At a bend radius of 30 mm, the critical current and n value remained the same as before bending. The total resistance of electrical terminations was 61 n Omega at 77 K. The flexible and transposed 6-around-1 star (R) cable can provide another route toward practical rebco conductors for high-field accelerator and fusion magnet applications.