Strain Distribution in REBCO-Coated Conductors Bent With the Constant-Perimeter Geometry

Journal Article · Tue Oct 24 00:00:00 EDT 2017 · IEEE Transactions on Applied Superconductivity

DOI:https://doi.org/10.1109/TASC.2017.2766132· OSTI ID:1420132

Wang, Xiaorong ^[1]; Arbelaez, Diego ^[1]; Caspi, Shlomo ^[1]; Prestemon, Soren O. ^[1]; Sabbi, GianLuca ^[1]; Shen, Tengming ^[1]

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1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Here, cable and magnet applications require bending REBa₂Cu₃O_7-δ (REBCO, RE = rare earth) tapes around a former to carry high current or generate specific magnetic fields. With a high aspect ratio, REBCO tapes favor the bending along their broad surfaces (easy way) than their thin edges (hard way). The easy-way bending forms can be effectively determined by the constant-perimeter method that was developed in the 1970s to fabricate accelerator magnets with flat thin conductors. The method, however, does not consider the strain distribution in the REBCO layer that can result from bending. Therefore, the REBCO layer can be overstrained and damaged even if it is bent in an easy way as determined by the constant-perimeter method. To address this issue, we developed a numerical approach to determine the strain in the REBCO layer using the local curvatures of the tape neutral plane. Two orthogonal strain components are determined: the axial component along the tape length and the transverse component along the tape width. These two components can be used to determine the conductor critical current after bending. The approach is demonstrated with four examples relevant for applications: a helical form for cables, forms for canted cos θ dipole and quadrupole magnets, and a form for the coil end design. The approach allows us to optimize the design of REBCO cables and magnets based on the constant-perimeter geometry and to reduce the strain-induced critical current degradation.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1420132
• Journal Information: IEEE Transactions on Applied Superconductivity, Journal Name: IEEE Transactions on Applied Superconductivity Journal Issue: 8 Vol. 27; ISSN 1051-8223
• Publisher: Institute of Electrical and Electronics Engineers (IEEE)
• Country of Publication: United States
• Language: English

Related Subjects

(REBCO RE = rare earth) coated conductors
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Bending strain
REBa2Cu3O7-δ
rectifying developable surface