High Performance 2G wires : From R&D to Pilot-scale Manufacturing

V. Selvamanickam, Y. Chen, X. Xiong, Y.Y. Xie, M. Martchevski, A. Rar, Y. Qiao,
R.M. Schmidt, A. Knoll, K.P. Lenseth, and C.S. Weber

Abstract—Tremendous progress has been accomplished in 2008 in key metrics of YBa2Cu3Ox (YBCO) second-generation (2G) HTS wires at SuperPower.  Using improved precursor chemistry in our Metal Organic Chemical Vapor Deposition (MOCVD) process, critical currents (Ic) as high as 813 A/cm were reached over meter-long lengths, representing the highest reported Ic in meter long 2G HTS. By use of Zr doping of (Gd,Y)Ba2Cu3Ox, strong enhancements were achieved in in-field performance over a wide angular range. A Ic of 229 A/cm was achieved at 77 K and 1 T perpendicular to the wire which is about a factor of 2.5 times better than that of standard MOCVD-derived films. At 65 K and 3 T, a Ic of 340 A/cm was demonstrated perpendicular to the wire. Kilometer lengths of 2G HTS have been demonstrated for the first time. Over 35 tapes 1,000 to 1,500 m in length with a complete 5-layer buffer stack have been routinely produced in our pilot-scale manufacturing facilities. An excellent in-plane texture of 6 to 7 degrees with a uniformity of about 2% was reproducibly achieved in the kilometer-long fully-buffered tapes. Using these high-quality buffers, the longest 2G wire length to date of 1,311 m was produced with a minimum Ic of 153 A/cm corresponding to a Ic ´ length value of 200,580 m. Also, an    1,030 m long complete 2G HTS wire has been demonstrated with a minimum Ic of 227 A/cm corresponding to a record Ic ´ length value of 233,810 A-m. Further, a 630 m long segment of the wire sustained a minimum Ic of 302 A/cm, the longest 2G wire reported to date with a Ic over 300 A/cm. Also, a Ic of 337 A/cm was achieved over a 540 m long segment. All these values represent a 2 to 3 fold improvement in length and Ic of 2G wires compared to our achievements in 2007. In 2008, a 30 m long 2G cable made with nearly 10,000 m of 2G wire previously delivered by SuperPower was successfully installed and energized in the grid of National Grid in downtown Albany, marking the world’s first of 2G HTS device in the power grid.

Index Terms—second-generation HTS, IBAD, MOCVD, cable, long length, critical current, BZO, Zr

Manuscript submitted on August 26, 2008.
The work at SuperPower was supported in part by contracts with the U.S. Department of Defense, U.S Department of Energy, and U.S. Air Force Research Laboratory. Part of the work was done under Cooperative Research & Development Agreements with Oak Ridge National Laboratory (ORNL), Los Alamos National Laboratory (LANL), and Argonne National Laboratory (ANL).
All authors are with SuperPower, 450 Duane Ave., Schenectady, NY 12304, U.S.A. (corresponding author: Venkat Selvamanickam,  now with the University of Houston, phone : 713-743-4044; fax : 713-743-4514; e-mail : selva@uh.edu)

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