R&D of coated conductors for applications in Japan

On the research and development of coated conductors in Japan, the Ic characteristics and the length have been remarkably improved in the national project. Five hundred meter-long tapes with higher Ic values than 300 A/cm-width were realized by the pulsed laser deposition (PLD) and the metal organic deposition using trifluoroacetates (TFA-MOD) processings for the superconducting layer on the IBAD-GZO buffered substrates. In order to realize the low cost by the increasing the production rate of the ion beam assisted deposition (IBAD) layer, the process of IBAD-MgO was developed and a 1000 m-long IBAD buffer tape was fabricated at an extremely high production rate of 1 km/h. On the other hand, the artificial pinning center has been introduced in both PLD and MOD processing. The BaZrO3 nano-rods were aligned along the c-axis of GdBCO superconducting films by the PLD process. The Jc value in the magnetic field parallel to the c-axis was remarkably improved. Additionally, the BaZrO3 nano-particles were uniformly dispersed in YGdBCO films by the TFA-MOD process and the Jc–B–θ property was confirmed to be isotropic.Based on the above-mentioned achievements, the new national project, whose main objective is the development of some electric power applications using a coated conductor, started in 2008. In this project, the improvement of the coated conductor includes the five sub-themes: (1) degradation of tapes, (2) high Ic under magnetic field, (3) low AC loss, (4) high mechanical strength and high Je and (5) low cost and high yield.