15T cryocooled Nb₃Sn superconducting magnet with a 52 mm room temperature bore

We succeeded in demonstrating a 15.1 T cryocooled Nb₃Sn superconducting magnet with a 52mm room temperature bore. Two operating currents of 157 A and 90 A for the divided section coils were utilized for the first time in a cryocooled superconducting magnet system. It is found that the current leads are no longer the dominant heat loads because of the use of high-temperature superconductors. In order to realize a high-field cryocooled superconducting magnet comparable to the usual superconducting magnet immersed in liquid helium at 4.2 K, we maintained the coil temperature at a value below 5.0 K during the field sweep in a high magnetic field region.