Development of ReBCO-CORC Wires With Current Densities of 400–600 A/mm $^2$ at 10 T and 4.2 K

Thin ReBCO tapes of 2 mm in width and only 30-<inline-formula><tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula>m substrate thickness allow production of thin CORC wires of 3–4 mm in diameter. These CORC wires feature high bending flexibility and high current densities as required for high field magnets. Two CORC wires, the first with 50 tapes and the second with 29 tapes, were developed and tested in a common effort of CERN, ACT, and the University of Twente. The two CORC wires were tested as small solenoids in transverse magnetic fields of up to 10.5 T and at 4.2 K. Afterwards, single tapes were extracted from the samples and tested individually in self field at 76 K. The first CORC wire had a critical current of 4255 A and an engineering current density of 322 A/mm<inline-formula><tex-math notation="LaTeX">$^2$</tex-math></inline-formula>, while the second wire showed 3970 A and 412 A/mm<inline-formula><tex-math notation="LaTeX">$^2$</tex-math></inline-formula>, both at 10 T and 4.2 K. The extracted tape analyses showed points of improvement for both wires, and therefore, provide valuable feedback for improving the wire production process and wire handling. CORC wire optimization resulted in no performance degradation of the 29-tape wire during electromagnetic load cycling at high magnetic fields. In this paper, details are presented on the CORC wires and measurement results are summarized.