Performance test of a refrigerator cooled magnet fabricated using Bi-2212 multilayer superconducting tapes

A stacked pancake coil was fabricated by Ag-alloy sheathed Bi-2212 multilay er tapes and tested using a refrigerator. The magnet consisted of ten doubl e pancakes wound with 100m class tapes. The I-c values of the tapes varied from 80A to 150A at 4.2K and 10T because of the scattering of the thickness in the superconducting layers. The magnet carried a critical current of 57 A at 12K and generated B-max of 1.4T in a 60mm bore. At 12K the magnet coul d operate with an operating current of 45A which corresponded to about 80% of I-c. Thermal runaway was not observed even with a ramp rate of 10T/min.