Abstract
RE–Ba–Cu–O (REBCO, RE = rare earth) symmetric tape round (STAR®) wires of 1.5–2.5 mm diameter have been fabricated with 4–12 strands of symmetric REBCO tape made by advanced metal organic chemical vapor deposition (MOCVD). 1.5 mm diameter STAR® wires made with just four advanced MOCVD tape strands are able to sustain nearly the same critical current (Ic)as 2.5 mm diameter wires made with 12 commercial-grade tape strands. An Ic of 1070 A, corresponding to an engineering current density (Je) of 597 A mm−2, has been demonstrated at4.2 K, 30 T in 1.5 mm diameter, four-strand wire at a bend radius of 15 mm. This Ic value exactly matches the Ic expected from the lift factor of the tape strands used in the wire. The2.5 mm diameter STAR® wires made with 12 advanced MOCVD tape strands exhibit an Ic of1075 A at 77 K, self-field and sustained currents of 2500–2750 A at 4.2 K, 30 T before burnout, corresponding to a Je greater than 500 A mm−2. These results show that the cost of STAR®wires can be substantially reduced using fewer tape strands of high-performance advanced MOCVD tapes and that the superior bend performance of STAR® wires can be maintained, even using 12 strands of advanced MOCVD tapes with 4 µm thick REBCO films.