Conveners
M1Or3A - Memorial Session: Dedicated to Prof. Tachikawa
- Hiroaki Kumakura (National Institute for Materials Science)
- Wilfried Goldacker (Karlsruhe Institute of Technology / ITEP)
When I joined Tachikawa's group in NRIM(now NIMS) in 1978, they have almost finished the research of bronze–process and they were carrying out many kinds of impurity additions to Nb3Sn wires. Soon they found that Ti addition is very effective to enhance Jc values at high field region. I measured Hc2 values of various impurity added bronze processed Nb3Sn wires at MIT, and found that Ti or Ta...
Superconducting Nb3Sn wires are actually in the focus to achieve enhanced high field performance, in particular for future advanced accelerator magnets of the next generation, by means of novel preparation methods to increase the flux pinning. It was learned already quite early in the development of the material that stresses and strains play an important role in the Nb3Sn system and strongly...
The discovery that small amounts of Cu enable the formation of V3Ga, Nb3Sn and other A15 compounds without intermediate Nb-Sn phase formation without needing to go to liquid reactions opened the path to fine A15 grain size and multifilamentary strand and all the applications that followed, from NMR to ITER and beyond. Nb3Sn tape then rapidly disappeared. In order to meet the needs of the next...
Prof. Kyoji Tachikawa always had strong interest for superconducting materials having high Jc in high magnetic fields. In 1980’s, his interests had moved from the bronze processed V3Ga and Nb3Sn wires to advanced Nb3Al and Nb3(Al,Ge) wires, which had much higher Bc2(4.2K) of over 30 T. The stoichiometric Nb3Al as well as Nb3(Al,Ge) required high temperature heat treatment about 2,000oC, so...
The recent progresses, properties, and future work of APC Nb3Sn conductors are reported. Great progresses have been made in the past two years in developing the APC Nb3Sn wires, including adding Ta dopant and improving wire recipe and quality. This has led to great improvement in their properties. The most recent APC wires have achieved Bc2 (4.2 K) above 28 T (1-2 T higher than conventional...
The construction of the Future Circular Collider (FCC) has very stringent requirements for Nb3Sn conductor critical current density, Jc, with a target non-Cu Jc(16T, 4.2K) of at least 1500 A/mm2. Nowadays the best commercial Nb3Sn strands can only reach 1300 A/mm2, consequently it will be necessary to significantly increase the...
