TEST COILS MADE OF TL-1223 TAPES

Silver sheathed Tl-1223 tapes were prepared by a powder-in-tube proces s. The critical current density of short samples was 18 kA/cm(2) at 77 K. Longer tapes up to 1.2 m, prepared by sequential pressing, had a c ritical current density of 12 kA/cm(2). From these tapes we have wound two coils. A solenoid coil with 5 windings was made of 8 tapes with a total length of 4.5 m. At 77 K the critical current of the coil was 2 3 A in the self generated magnetic field (18 Gauss at the centre of th e coil). Using an iron yoke the critical current remained at 22 A whil e the generated magnetic field increased to 120 Gauss. A pancake coil with 15 windings, made of 5 tapes with a total length of 5 m, generate d a magnetic field of 149 Gauss at the critical current of 12 A. From measurements of the critical current density of our tapes in applied m agnetic fields, we conclude that coils made of Tl-1223 tapes can be us ed to generate higher magnetic fields at 77 K.