Highlights in R&D for coated conductors in Japan

The current 5-year national project since 2003 for development of coated conductors (CC) using Y-system superconductors has passed for almost a half term and has achieved satisfactory results. In this paper, the current status and the future prospect are reviewed. The group of Fujikura Ltd. and SRL-ISTEC has worked on the long tape with high performance in the PLD-YBCO superconducting tapes on the IBAD-Gd2Zr2O7 buffered substrates. The highest value on the product of I-c x L in the world was marked by the result which were 51,940 A in (212 in x 245 A) by the SRL group. Fujikura Ltd. also realized the longest tape of 200 in with a reasonable high I-c value of 100 A. The values have been steadily improved and the trend is going to be continued, since the large equipments for both MAD and PLD have been installed, and ready to work on large tapes with a high production rate. In another group, the long tape processing has been developed focusing on lowering the production cost. The extremely high I-c value of 470 A was obtained in the film by the TFA-MOD method on CeO2 (PLD)/GZO(IBAD)/hastelloy substrate. In the efforts for the long tape in the process, a 25 in long tape with its I-c value of 100 A was realized by a continuous reel-to-reel system. Additionally, 100 in class long tapes were also obtained by the MOCVD and PLD-HoBCO processes. Both groups are aiming to achieve the final goals of 500 in long tapes with the high I-c value of 300 A/cm-w by the production rate of 5 m/h. Furthermore, the feasibility study for applications using coated conductors has been already started due to the above-mentioned success of long tape production. Several kinds of coils using long coated conductors such as a solenoid and a pancake coils and the spiral shaped conductors for cable applications were firstly made. Reasonable high performances were confirmed in the trials. For the future plans of coated conductor applications, the following power devices using coated conductors have been proposed; (1) power cable, (2) transformer, (3) motor, (4) fault current limiter, (5) cryocooler, and so on. (c) 2006 Elsevier B.V. All rights reserved.