Persistent mode operation of Bi2Sr2CaCu2Ox/Ag stacked double pancake coils with superconducting joints

A persistent current mode magnet was successfully fabricated using Bi2Sr2CaCu2Ox/Ag tapes. The magnet system consisted of four Bi2Sr2CaCu2Ox/Ag double pancake coils as a magnet and a noninductively wound Bi2Sr2CaCu2Ox/Ag-Au single pancake coil as a persistent current switch. The pancakes were stacked and jointed using a butt-jointing method to form a superconducting closed loop. Persistent current mode operation of the magnet was initiated in liquid helium, trapping a magnetic field of 1T which corresponds to a loop current of 134A. The voltage-current (V-I) characteristic of the closed loop was estimated from the decay of the trapped field. An index number in the V-I curve, n, above 30 and a loop resistance of 2 x 10(-10) Omega were observed for the loop current above 30 A after 116 hours.