Small REBCO isotropic round wire (STAR): an important step from performant material to practical conductor in high field HTS magnets

Rossi, L.

doi:10.1088/1361-6668/ab3699

Cited by 3 publications

(1 citation statement)

References 13 publications

(14 reference statements)

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“…Even higher gains in beam energy and luminosity can be obtained by using hightemperature superconductor (HTS) dipoles, which are the only option for field strengths in the vicinity of 20 T [5][6][7][8][9][10]. The development of practical, high-current-density round isotropic wires from REBa 2 Cu 3 O 7 (REBCO, RE = rare earth) tapes, for use as a single strand conductor or as a sub-element of a complex cable, may constitute a real breakthrough in magnet technology [11]. REBCO tapes have already been deployed in user-oriented high-field magnets for very highfield (30 T range) solenoids for laboratory measurements and new frontier nuclear magnetic resonance beyond 1 GHz [12,13].…”

Section: Introductionmentioning

confidence: 99%

Progress in scale-up of REBCO STAR™ wire for canted cosine theta coils and future strategies with enhanced flexibility

Kar

Sandra

Luo

et al. 2020

Supercond. Sci. Technol.

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We report recent developments in the scale-up of symmetric RE-Ba-Cu-O (REBCO) tapes with 15-22 µm thick substrates. Using these symmetric REBCO tapes, we fabricated up to 10 m long, symmetric tape round (STAR™) REBCO wires, less than 2 mm diameter, using 1.02 mm and 0.81 mm diameter copper formers. The critical current of the long STAR™ wires made in lengths of 2-10 m ranges from 465 A to 564 A at 77 K, self-field. This wire was then used to construct a single-layer, full-depth groove, three-turn canted cosine theta (CCT) coil with a minimum bend radius of 15 mm. This three-turn CCT coil retains 95% of its I c even when wound at a such a small bend radius. This result confirms the capability of fabricating CCT coils with STAR™ wire at a tilt angle of 30º which would yield a dipole transfer function of 0.48 T kA −1 at a 15 mm bend radius. Further, the architecture of STAR™ wire was modified for an I c retention of >90% at an even smaller bend radius of 10 mm with the aim of increasing the dipole transfer function. The higher dipole transfer function enabled by STAR™ wire is an important step toward the eventual goal of a 5 T maximum dipole field in a REBCO-based CCT coil. At a bend radius of 10 mm, a six-layer STAR ™ wire exhibits a critical current of 288 A at 77 K, self-field, i.e. 94% I c retention and 617 A at 4.2 K in a 15 T background field, which equals a J e of 412.7 A mm −2 at a Lorentz force of 9.3 kN m −1 . This level of flexibility and the high performance of STAR ™ wire in high fields at 4.2 K and with a small bend radius underscores its potential use in compact and low-cost high-field magnet and related applications.

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