||為ヶ井 強 准教授
||High-field magnet using stacked coated conductors
||Cuprate superconductors (RE)Ba2Cu3O7 (RE: Rare Earth, and it is called REBCO), which have higher critical current density than other superconductors at high temperatures and high fields, are expected to be used for superconducting cables and magnets. The commercially available REBCO coated conductors, which are thin tapes, can be cut and stacked to form a stacked magnet. To date, there have been many studies on stacked magnets because they can be applied for NMR, motor, etc.
We have fabricated stacked magnets using EuBCO coated conductor with BaHfO3 nanorods (Fujikura Ltd.). In the previous study , we observed extended regions of irregular flux penetration called “flux jet”  originated by cutting-induced damages of coated conductors in magneto-optical images. When we compared the experimental results with the calculation result of trapped fields of the stacked magnet, there was discrepancy between them, and it can be understood by considering the reduction of the effective size of the stacked magnet due to the flux jet. In order to obtain better stacked magnet than the previous study, we improved the fabrication process so that the effect of cutting-induced damages in coated conductors becomes minimum. As a result, we have succeeded in magnetizing the stacked magnet than previous study and trapping 16.5 T of field at 10 K.
I will also discuss the plan to obtain a higher trapped field in the future study.
 M. Suyama et al., Supercond. Sci. Technol. 34 065004 (2021).
 A. Gurevich et al., Phys. Rev. B 62 4004 (2000).