Exfoliated YBCO filaments for second-generation superconducting cable

• Published in: Superconductor science & technology Vol. 30; no. 1
• Main Authors: Solovyov, Vyacheslav, Farrell, Paul
• Format: Journal Article
• Language: English
• Published: United States IOP Publishing 15.11.2016
• Subjects: 2G conductors; cable; exfoliation; MATERIALS SCIENCE
• ISSN: 0953-2048

The second-generation high temperature superconductor (2G HTS) wire is the most enticing conductor for high-field magnets such as accelerator dipoles and compact fusion devices. The key element of the wire is a thin Y1Ba2Cu3O7 (YBCO) layer deposited on a flexible metal substrate. The substrate, which becomes incorporated in the 2G conductor, reduces the electrical and mechanical performance of the wire. This is a process that exfoliates the YBCO layer from the substrate while retaining the critical current density of the superconductor. Ten-centimeter long coupons of exfoliated YBCO layers were manufactured, and detailed structural, electrical, and mechanical characterization were reported here. After exfoliation, the YBCO layer was supported by a 75 μm thick stainless steel foil, which makes for a compact, mechanically stronger, and inexpensive conductor. The critical current density of the filaments was measured at both 77 K and 4.2 K. The exfoliated YBCO retained 90% of the original critical current. Similarly, tests in an external magnetic field at 4.2 K confirmed that the pinning strength of the YBCO layer was also retained following exfoliation.