Test Results of Conduction-Cooled Bi-2223 Magnet With Shield Coils at Both Ends

We have designed and fabricated a superconducting magnet using (Bi,Pb)
₂
Sr
₂
Ba
₂
Cu
₃
O
₁₀
(Bi-2223) tape conductors. This magnet is a model magnet for a magnetic refrigeration system for hydrogen liquefaction. The magnet consists of three coils: a main coil and two shield coils. The shield coils generate opposite direction magnetic fields to reduce the magnetic fields to zero at both ends. The Bi-2223 magnet successfully generated a rated field of 4.8 T at the center at 20 K operation. The performance of the magnet at higher operating temperatures was also investigated. The temperature dependence of the performance of this magnet agreed with
I
_c
estimated from the properties of the Bi-2223 tape used at the position of the maximum radial magnetic field in the magnet.