Highlights of coated conductor development in Japan

Coated conductors using RE-Ba-Cu-O (RE: rare earth element) superconductors have been expected to be used in many electric power applications since they have a high critical current density at liquid nitrogen temperature even under high magnetic fields. Many efforts have been made in development of processing for a long coated conductor with high superconducting performance. In Japan, the new five-year national project for development of coated conductor processing was started in FY2003 and was scheduled until the end of FY2007. The expected goals in this project are 500 m long tapes with a high I_c value of 300 A cm^-1W^-1 at a production rate of 5 m h^-1 etc. The progress in recent years is remarkable, such as long tapes over 100 m in length with high I_c values of over 100 A cm^-1W ^-1. The long tapes have been successfully realized by not only one institution but several. Additionally, a solenoid type magnet and a power cable using YBCO conductors have already been demonstrated as one of the preliminary results for applications. 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.