HTS Accelerator Magnets and Conductor development in Europe

Sandra

et al. 2020

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.

Section: Introductionmentioning

confidence: 99%

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

Sandra

et al. 2020

“…For the HL-LHC, about 30 Nb 3 Sn quadrupoles with peak fields above 12 T and 20 Nb 3 Sn dipoles with peak fields in excess of 11 T will be produced. Even higher gains in beam energy and luminosity for the proposed High Energy LHC can be obtained by using high temperature superconductors (HTSs) which are the only option for field strengths in the vicinity of 20 T [1,4].…”

Section: Introductionmentioning

confidence: 99%

Symmetric tape round REBCO wire withJ_e(4.2 K, 15 T) beyond 450 A mm⁻²at 15 mm bend radius: a viable candidate for future compact accelerator magnet applications

Yahia

et al. 2018

Due to an error in the production process, the title of this article should read 'Symmetric Tape Round (STAR) REBCO wire with J e (4.2 K, 15 T) beyond 450 A mm −2 at 15 mm bend radius: a viable candidate for future compact accelerator magnet applications'. Furthermore, all references to 'symmetric tape round wires' should be 'Symmetric Tape Round (STAR) wires'.In the 'Tape preparation' subsection 'The REBCO tape was then slit from a width of 12-2.5 mm using a reel-to-reel laser slitting machineK' should read 'The REBCO tape was then slit from a width of 12 to 2.5 mm using a reel-to-reel laser slitting machineK'.

“…Superconducting magnets using low temperature superconductors such as Nb 3 Sn are generally limited to magnetic fields not exceeding 20 T [1]. For applications that require operation at higher magnetic fields or at a temperature above 4.2 K, high temperature superconductor (HTS) magnets are essential [2,3]. Applications that can benefit from high-field HTS magnets include high energy physics [4], superconducting magnetic energy storage [5], nuclear fusion [6] and other science and research projects.…”

Section: Introductionmentioning

confidence: 99%

Superior critical current of Symmetric Tape Round (STAR) REBCO wires in ultra-high background fields up to 31.2 T

et al. 2018

Symmetric Tape Round (STAR) wire fabricated with an ultra-thin RE-Ba-Cu-O (REBCO, RE=rare earth) coated conductor has a high engineering current density (J e ) and remarkable flexibility. It is a competitive candidate for future canted cosine theta magnets with smaller winding radii that operate at fields above 20 T at 4.2 K. STAR wires consisting of six or eight REBCO coated conductor layers have been fabricated with an outer diameter smaller than 2 mm. We performed in-field tests of the critical current of STAR wires at 4.2 K in background fields up to 31.2 T. At a 15 mm bending radius, J e values of 438 A mm −2 at 20 T and 299 A mm −2 at 31.2 T were obtained. These are the highest J e values measured in any reported round-geometry REBCO wires at such ultra-high background magnetic fields. This exhibits the potential of STAR wires in future compact accelerator magnets.