Bi-2211/Ag superconducting insert magnet for high magnetic field generation over 22T

A superconducting insert magnet using Bi-2212/Ag multifilamentary tapes for high magnetic field generation has been successfully fabricated. The coil was made by a wind and react process and included a stack of four double pancakes. The dimensions of the stacked coil were 55 mm in height, 49 mm in outer diameter and 12.5 mm in clear core. The coil was inserted in a 21 T-class superconducting magnet and tested various backup fields at 4.2 K. The maximum magnetic field at the center B-0 of the coil reached 1.76 T under a backup magnetic field of 21 T: i.e.: the magnetic field generated by the superconducting magnet system reached 22.8 T. The critical current density J(c) of the Bi-2212 core and the coil current density J(c)-coil reached 951 A/mm(2) and 128 A/mm(2) respectively. These J(c) values are high enough for high field magnet applications such as 1 GHz-class NMR magnet.