Cryocooler-cooled high field superconducting magnet

A high field NbTi/Nb3Sn superconducting magnet with no use of liquid helium was developed by adopting high-Tc Bi2Sr2Ca2Cu3O10 current leads and 4 K GM-cryocoolers. The initial cooldown from room temperature to 4.1 K for the coil was attained within 40 hours by conductively cooling in vacuum. The cryocooler-cooled superconducting magnet successfully achieved to generate a central field of 10.7 T in a 52 mm room temperature experimental bore, and to hold a field at 10.5 T for 24 hours.