Manufacture and Test of a 5 T Bi-2223 Insert Coil

With the goal of obtaining a magnetic field of 25 T in our facility HOMER II with a superconducting LTS-HTS hybrid magnet, a first prototype 5 T high temperature superconducting (HTS) insert coil has been constructed and tested. The HTS insert consists of 16 double pancakes made of stainless steel reinforced Bi-2223 tapes manufactured by American Superconductor. The HTS coil was operated at 1.8 K and produced 5.4 T at a current of 151.2 A. In a background field of 11.5 T provided by our facility HOMER I, a total field of 16.9 T was obtained several times. No training or quench of the coil was observed during the test, but after warming up a defect in the winding of one double pancake was detected, presumably due to a ballooning of the tape. The design of the coil and the results of the test are presented and discussed.