Development of defect repair method of superconducting film with damage of scratch

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K22157
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 31:Nuclear engineering, earth resources engineering, energy engineering, and related fields
• Research Institution: Kyushu University
• Principal Investigator: Teranishi Ryo 九州大学, 工学研究院, 教授 (70415941)
• Project Period (FY): 2019-06-28 – 2022-03-31
• Keywords: 酸化物超伝導 / 線材 / 薄膜 / 結晶配向 / 接合 / 熱処理 / 機械的圧力 / 微細組織

Outline of Final Research Achievements

GdBa2Cu3Oy(GdBCO) superconducting tape has high critical temperature above 90 K and high critical current at liquid nitrogen temperature, so the tape has been expected to operate as long length wires. Nevertheless, devices using the tapes have not been commercialized yet, due to the difficulty for fabricating long length tapes. If a very small number of defects are found in the superconducting layer, the current value at the defect becomes the upper limit of the current value of the total length of the wire, and it is necessary to cut the wire at the defective part. In this study, superconducting joints of GdBCO tapes were prepared to for the purpose of partially repairing the defective part.
As results, we found important factors to join superconducting layer with high crystal orientation; heat-treatment temperature of jointing, mechanical pressure and partial pressure of oxygen during heat-treatment. Finally, we found optimum condition to join the tapes with high orientation.

Free Research Field

機能性無機材料

Academic Significance and Societal Importance of the Research Achievements

本研究では、GdBCO超伝導薄膜線材を高い結晶配向で接合するための条件を明らかにすることができた。得られた成果は、超伝導線材に生じた極微小な欠陥部位を局所的に補修する技術に展開することができ、これまで欠陥部位で線材を切断していたがその必要がなくなるため長尺線材の作製において歩留まりが飛躍的に向上するものと期待され、高性能な線材を量産供給することによる超伝導技術の普及への一助となる。