Friday, 2E-19, -

Development of Application-Ready Second-Generation HTS Wire

Yi-Yuan Xie

K. Lenseth, M. Marchevsky, Y. Chen, X. Xiong, Y. Qiao, A. Rar, R. Schmidt, A. Knoll, D. Hazelton, and V. Selvamanickam

SuperPower, Inc., 450 Duane Ave., Schenectady, NY 12304, USA.
Phone: 518-346-1414; Fax: 518-346-6080; e-mail: yxie@superpower-inc.com.

SuperPower’s 2G HTS wire technology is based on IBAD-MgO for textured buffer template and MOCVD for REBCO HTS layer. Recently we reported 2G HTS wires with single piece length (L) more than 1 km and critical current at 77 K and self-field (Ic (77K, 0T)) above 227 A/cm-w. While continuing to improve I_c (77K, 0T) and L, the application-readiness of 2G HTS wire has been one of the focuses of our technology development, in which performance parameters including in-field I_c, ac losses, joints, insulation, and fault current limiting performance are investigated in order to meet the technical requirements for real-world applications including transmission cables, superconducting magnets, fault current limiters, motors and generators. This paper will report the progress in the development of application-ready 2G HTS wire. Artificial pinning centers such nano-precipitates, nano-clusters and nano-rods have been induced into MOCVD-based REBCO films through modification of chemical composition, and significant enhancement in in-field performance has been shown in magnetic fields parallel and perpendicular to the wire surface and at intermediate angles as well. ROEBEL conductor is a proven technology to reduce ac loss through the transposition of current flow. In a ROEBEL conductor, current flows along the wire length and across the wire width, which poses a unique challenge to 2G HTS fabrication since two-dimensional (2D) uniformity is required; we developed a technique to analyze the 2D uniformity based on magnetic measurement results and compared with transport current measurement results. For joints, we have developed a production operation so that the joint resistance can be maintained consistently low at ~33 nano-ohm for 10 cm long joints. Wire with insulated with polyimide films is routinely fabricated with our in-house insulation machine and also demonstrates good performance. These developments in application-readiness will promote the wide use of 2G HTS wire.

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