A superconducting coil with high-strength CuNi-NbTi/Nb3Sn wire was fabricated using the react and wind (R&W) technique. The CuNi-NbTi/Nb3Sn wire indicated a high 0.2% proof stress at a room temperature of 340 MPa, which is much larger than the conventional Cu/Nb3Sn wire of 150 MPa. The dimensions of the Nb3Sn coil produced using the R&W technique are 260 mm in inner diameter, 289 mm in outer diameter and 319 mm in height. It is designed to generate a central field of 2.18 T at 180 A. The superconducting CuNi-NbTi/Nb3Sn coil was inserted into a previously fabricated cryocooled backup NbTi coil and a field of 5.85 T was generated in the coil center. The constructed cryocooled superconducting magnet has a room temperature bore of 220 mm in diameter and is designed to generate a central field of 8 T. Consequently, the superconducting magnet generated 7.5 T at its maximum and 7 T stably for 12 hr.
