Engineering current density in excess of 200 A mm⁻²at 20 T in CORC^®magnet cables containing RE-Ba₂Cu₃O_7−δtapes with 38μm thick substrates

Abstract

Conductor on round core (CORC ®) cables wound from RE-Ba 2 Cu 3 O 7−δ coated conductors are currently being developed for the next generation of accelerator magnets because of their high flexibility and potential for high engineering current densities J E. CORC ® cables previously reached J E of 114 A mm −2 at 4.2 K and 20 T in a 7.5 mm diameter cable. Accelerator magnets require a current density of at least 300 A mm −2 and a cable-bending diameter as small as 40 mm, which has so far not been possible with superconducting tapes made on 50 μm thick substrates. CORC ® cables made from thinner substrates could have significantly increased J E with greater flexibility as we here demonstrate with a CORC ® cable made of tapes with 38 μm thick substrates. A custom cable machine produced higher cable quality and better retention of tape performance compared to previous cables that were wound by hand. The thinner substrate showed an almost twofold increase in engineering current density from 114 A mm −2 to 216.8 A mm −2 at 4.2 K and 20 T, at a reduction in cable diameter from 7.5 mm to 6.0 mm. The results clearly demonstrate that winding CORC ® cables from tapes with thinner substrates is a straightforward method for raising their current density and one that shows great promise for use in accelerator magnets.

Introduction of CORC®wires: highly flexible, round high-temperature superconducting wires for magnet and power transmission applications

“…Critical current measurements were performed in 0 to 10 T background field at 4.2 K. At each run, the current was ramped up in small steps and settled on each plateau for 3 second before the voltage was recorded. There is a limit on the strain that can be applied to the REBCO layer as the coated conductor is bent around a former before irreversible degradation of I c occurs [9]. The strain (ε) at the YBCO interface can be calculated using the equation:…”

Compact steady-state tokamak performance dependence on magnet and core physics limits

“…Furthermore, as Btrueprefixmax is increased to 19 T [30], higher J WP ≈ 30 MAm −2 is required to access this higher maximum magnetic field for A ≥3.5. Progressively higher J WP up to 160 MAm −2 [31,32] is required to reach Btrueprefixmax=19 T for nearly all aspect ratios, i.e. for A ≥1.8.…”

Toward 20 T magnetic resonance for human brain studies: opportunities for discovery and neuroscience rationale

“…This is a very active field of research at present with various HTS materials (YBCO, Bi2212, Bi2223) being cabled in a number of configurations in the pursuit of ultrahigh-field large magnets. At present, the accelerator community has been leading the development of Conductor on Round Core using YBCO tape [20] and the Rutherford cable based on Bi2212 round-wire [21]. The fusion community has championed twisted stacks of YBCO tape [22].…”