Roebel cable for high-field low-loss accelerator magnets

In the past 40 years, the high energy physics (HEP) program has driven the development of superconducting magnet technology. NbTi and Nb₃Sn have reached their performance limits with upper critical fields (H_c2) of 14 T and 29 T, respectively, limiting magnetic field generation to about 10.5 T and 20 T [1-3]. YBa₂Cu₃Oy (YBCO) coated conductors are capable of generating very high magnetic fields, but are limited by a flat tape geometry and subsequent high AC losses. Roebel cables create a filamentary type structure and provide transposed current percolation paths, reducing these AC losses. Performance testing of YBCO Roebel cables exist only for high temperature (50-77 K) regimes in self-field and are limited to studies on critical current density and AC losses. There exists a need to characterize YBCO Roebel cables at low temperature (4.2 K) and varying magnetic fields to determine their electromagnetic and mechanical properties, and evaluate their viability in high field low loss accelerator magnets.