Speaker
Description
We are studding the superconducting joint between multi-filamentary Bi2223 tapes with incongruent melting (JIM) method, to develop a high-field 1.3 GHz-NMR in Japan. We obtained critical currents of 12 A at 77 K and 177A at 4 K for the reinforced HT-NX type wire in early stage of the study [1], and a high critical current above 50 A at 77 K was obtained in non-reinforced H type wire [2]. For application in NMR magnet, improvement of the critical current in the HT-NX type wire is necessary. In this study, we developed a multi-spot heating device having two heating stages that two junctions can be heat treated simultaneously. In experiment, a joint sample with 5 junctions was prepared at 850 °C for a short time of 30 s. The critical current was measured at 77 K. The result shows that total critical current of the 5 junctions was about 23 A, and this value is about 2 times than that of previous result in HT-N type wire. To investigate the effect on total critical current in each junction, we also measured the critical current for the 4, 3, 2, and single junctions, by cutting off the junctions one by one from then end junction. The results will be presented in upcoming MT27.
Acknowledgements:
This work was supported by JST-Mirai Program Grant Number JPMJMI17A2, MEXT project of Leading Initiative for Excellent Young Researchers (LEADER) Project ID 16810210, and JSPS KAKENHI Grant Number JP18K04719, Japan.
[1] X. Jin, Y. Suetomi, R. Piao, Y. Matsutake, T. Yagai, H. Mochida, Y. Yanagisawa, H. Maeda, Supercond. Sci. Technol., vol. 32, 2019, Art. no. 035011.
[2] Shintetsu Kanazawa, IEEE Transactions on Applied Superconductivity, vol. 31, 2021, Art. no. 7000104.
