Professor Masashi Miura of the Graduate School of Science and Engineering, Narumi University has improved the process of forming the superconducting layer of the yttrium-based oxide superconducting wire of high-temperature superconductors in collaboration with the Industrial Technology Research Institute and Showa Electric Wire Cable System Co., Ltd. Achieved the world's highest critical current density in a magnetic field.
Superconducting magnets for equipment used in environments where high magnetic fields are applied, such as motors, generators, and medical equipment such as MRIs and heavy particle beam accelerators, require wires that can maintain high performance even in magnetic fields.The yttrium-based oxide superconducting wire has higher performance in a magnetic field than other high-temperature superconducting materials, but there are problems such as the wire being expensive and the critical current performance in a magnetic field is not sufficient at high temperature and high magnetic field. was there.
This time, the research group reduced the film thickness applied at one time from the conventional 150 nm or more to 30 nm in a process called multi-coating (a process of repeating application and heat treatment on the substrate).As a result, the artificial pinning points in the formed superconducting layer could be miniaturized from the conventional 20 nm to about 10 to 13 nm.As a result, the critical current density in a liquid nitrogen temperature (65K) and a magnetic field of 3 tesla improved from about 1 million amperes to 2 million amperes per cm100.
Based on this basic principle, we succeeded in further improving the performance by selecting artificial pinning point materials and increasing the concentration, and the critical current density in liquid nitrogen temperature (65 K) and magnetic field 3 tesla is 11 million amperes per 2 cm400. Achieved.This is the highest value in the world for yttrium-based oxide superconducting wires at this time.In addition, the critical current value exceeded 360 amperes.
Showa Densen Cable System, which already manufactures and sells yttrium-based oxide superconducting wires, plans to develop products based on this result.AIST and Seikei University will continue to support practical application by developing high-performance technology.
