A review of commercial high temperature superconducting materials for large magnets: from wires and tapes to cables and conductors

Abstract

High Temperature Superconducting (HTS) materials have the potential to generate magnetic field beyond the level obtainable with Low Temperature Superconducting (LTS). This review reports the past and present R&D on HTS cables and conductors for high field tokamaks, accelerator dipoles and large solenoids. Among the HTS wires and tapes available commercially, coated conductor tapes are the most appealing because of the outstanding critical strength and large improvement margin. Limitations are the weakness against peeling and shearing and the short piece length. The prices for technical superconductors are reviewed because they play an important role in large projects; moreover the perspective of industrial production of HTS wires and tapes is discussed considering the historical development of the LTS wire market. Various designs have been proposed for HTS cables and conductors: some are better suited for soft materials, while others can exploit the anisotropy of coated conductors (by aligning the tape with the field), providing the highest current density. The last decade has seen an increase in the size and complexity of the prototypes; however some peculiar features of HTS, such as high stability margin and high mechanical limits, have not yet been fully incorporated in the designs: for example the transposition requirements for HTS have not yet been studied in detail. Several facts indicate that tapes (even if anisotropic) can be used for manufacturing cables and magnets of any size and have advantages with respect to round wires.

Dipole Magnets above 20 Tesla: Research Needs for a Path via High-Temperature Superconducting REBCO Conductors

“…As a closing remark to this section, we recognize that along with the HEP community, the fusion community has consistently identified REBCO high-field magnets as a transformative enabling technology for the magnetic fusion devices towards energy generation [203][204][205][206][207][208][209]. With the strong synergy between the high-field accelerator and fusion magnets [19,142,210], the research needs discussed here can also be leveraged for the development of high-field fusion conductors and magnets (Table 2). Table 2.…”

“…One solution is to fully impregnate the coil [141], consistent with the significantly improved resilience to the transverse pressure in impregnated Roebel cables [37,111,112]. On the other hand, solder-filled REBCO fusion conductors still show degradation [19,142].…”

“…It allows us to measure the mechanical resilience of HTS inserts under high Lorentz load and to provide early feedback to the development of REBCO conductor and magnet technology. Today's high cost of REBCO conductors (Table 1) also favors the hybrid approach to achieve 20 T, although the cost can significantly reduce due to the low raw material cost, given enough production and yield volume [19,25,96].…”

“…These technical superconducting materials are currently commercially available and relevant for high-field superconducting accelerator magnet applications. The attempt here benefits from earlier comparisons [19][20][21][22][23][24][25][26]. The Nb-Ti conductor is represented by the one for the LHC main dipole [24].…”

Nanosized Pinning Centers in the Rare Earth-Barium-Copper-Oxide Thin-Film Superconductors

“…Balancing of these components is no mean feat, but as the worldwide production of thin-film, REBCO superconductors has matured and high-performance coated conductors are currently readily available worldwide. Coated superconductors of the second generation in general and REBCO coated superconductors particularly are especially useful for application in large and very large magnets in steady-state, where they are more economical alternative to standard resistive magnets, especially for maintenance and electricity costs and are the only sound alternative for generating large magnetic fields in large volumes [59]. Finally, the most significant advantage of coated REBCO superconducting tapes, in comparison with the other types of superconducting tapes, is the high value of critical stresses at cryogenic temperatures: over 800 MPa in the longitudinal tensile direction [60].…”