Bending performance of the CORC cable with flexible interlocked stainless steel former

Abstract The high temperature superconducting cable on round core (CORC) is a kind of cable that could be used in fusion projects. Nevertheless, conventional copper former CORC cables require a large external force to allow the cable to endure plastic deformation and be tightly wound into solenoids. In this case, the superconducting tape will be affected by concentrated stress, resulting in a risk of critical current degradation. Therefore, this paper proposes a new CORC cable with flexible interlocked stainless steel former, which can be wound into a solenoid by applying a small external force. To verify the bending performance of this interlocked former CORC cable, a double-layer and a ten-layer interlocked stainless steel former CORC cable, as well as a double-layer traditional copper former CORC cable, are fabricated. And these three CORC cables are used to wind solenoids of various radius sizes respectively. The experimental results show that the critical bending radius of the double-layer interlocked stainless steel former CORC cable is less than 20 mm, the critical bending radius of the ten-layer interlocked stainless steel former CORC cable is less than 50 mm, and the critical bending radius of the double-layer traditional copper former CORC cable is larger than 55 mm. A self-consistent finite element model for the critical current of the CORC cable solenoid is also established. And the critical current experimental results are in good agreement with the simulation results. The results of this paper verify the excellent bending performance of the interlocked former CORC cable, which provides a good option for the preparation of insert magnets for future fusion projects.