Development of high temperature superconducting coils using Bi-2223/Ag tapes

Four double wound pancakes with inner diameters of 98 mm have been successfully fabricated with multifilamentary Bi-2223/Ag tape using the react and wind technique. Two pancakes were impregnated with wax and the other two with resin. The pancakes have been tested at 77 K producing critical current (I/sub c/) values up to 14.5 A and index of transition values (n) of up to 11.4. The field profiles produced by the pancakes have been modelled. The I/sub c/ field dependence of short samples of the component Bi-2223/Ag tape has been studied. I/sub c/ is most sensitive to field when the field is parallel to the c-axis of the tape, reducing I/sub c/ from 28 A to 13.2 A between 0 T and 30 mT. Although the bending strain of the tape in the coil is /spl sim/0.3%, the fabrication procedure for the pancakes has produced very little handling damage to the tapes. It is demonstrated that the I/sub c/ of the coils is almost entirely self field limited.