A Bi-2223 superconducting magnet has been designed and fabricated as a model magnet for a magnetic refrigeration system for hydrogen liquefaction. The magnet consists of three coils, i.e., a main coil and two shield coils. The two shield coils are differentially connected to the main coil to minimize the magnetic field at both ends. The magnet was made by stacking double pancakes impregnated with epoxy resin. The magnet is cooled by a 4-K Gifford-McMahon (GM) cryocooler. Heaters are also installed to test performance at temperatures above 20 K. The magnet successfully generated the rated field of 4.8 T at the center at 300 A, not only at 4 K but also at 20 K. Performance at higher temperatures of 30 K – 77 K are also tested.
G. Nishijima, M. Amaya, T. Nishimura, K. Kamiya, and T. Numazawa, IEEE Trans. Appl. Supercond. 33 (2023) 4602605.
This work was supported by JST-Mirai Program Grant Number JPMJMI18A3, Japan.