Design and fabrication of layer-wound YBCO solenoids

Rare Earth based coated conductors are very promising conductors for the construction of high field solenoids. Development of coil winding technique was started at the Tsukuba Magnet Laboratory: coils of various sizes (from 18 mm to 220 mm of an inner diameter) have been fabricated by layer-winding without impregnation in order to test the mechanical and superconducting properties. In the thin 220 mm diameter coil the Hoop stress reached over 500 MPa at 130 A in 14 T background field, without degradation of the superconducting properties. In the small diameter coils (18 mm of inner diameter) the tape was insulated using enamel to minimize the cross section and to enhance the coil current density. The highest field generated was 2.1 T in a background field of 18 T (total field was 20.1 T) at 4.2 K and the coil current density was 240 A/mm2.