Progress in research, development, and pre-commercial deployment of second generation HTS wires in the USA

US efforts to develop and deploy "second generation" (2G) high-temperature superconducting (HTS) wires that use the compound Y1Ba2Cu3Ox (YBCO) or other rare-earth (RE) superconducting materials are described. Wires have been demonstrated in 20 to > 200-m lengths with the YBCO deposited using vapor deposition or wet chemical processes in ultra-thin layers onto textured, buffered metallic templates, which forces the grains of the RE-BCO into near perfect alignment. Critical currents for these pre-commercial wires are now within striking distance of those achieved for commercial BSSCO wires. One expected advantage of 2G wire is a 5-fold decrease in the price of wire compared with first generation wires. Another advantage of 2G wire is the intrinsic behavior of YBCO in the presence of a strong magnetic field. Enhancements in flux pinning of at least a factor of two have been demonstrated for MOCVD and MOD deposited YBCO films. US progress towards meeting the challenging goals for the year 2006, including current exceeding 300 A/cm width (77 K, self-field) in 100-m lengths and engineering current density exceeding 10,000 A/cm(2) (65 K, 3-T) is reported. In addition, initial efforts toward engineering the conductor for the mechanical and electrical properties needed for strong magnetic field applications are described. (c) 2006 Elsevier B.V. All rights reserved.