Development and successful testing of the first Nb$_{3}$Sn wound, in-situ-reacted, high-field superconducting quadrupole of CERN

Following an extensive development of the "wind and react" technology of high-field and high-current density, Cu-stabilized Nb$_3$Sn cables, a sizeable, 1 m long, 9 cm bore, 100 KJ superconducting quadrupole magnet has been built and successfully tested and operated. Specific technological and design aspects of this magnet will be described, such as the simultaneous reaction process and heat treatment of the quartz insulation and solutions to problems of interconnections, the coil manufacture and the assembly of the active part of the magnet given. The quadrupole has been successfully tested and operated. The maximum current of 1.1 kA corresponds to an overall current density over the cross-section of the insulated cable of 3 × 10$^4$ A/cm$^2$ at a maximum field of 8 T (within 0.2 T) and was reached after only 5 quenches. These figures correspond to 93-99% of the critical current densities, measured on cable samples, reacted with each pole winding of the quadrupole. The nominal current of 1 kA was reached without quench and repeatedly maintained for several days. We believe that this new technology and the successful development of the first high-field, Nb$_3$Sn-cable-wound quadrupole magnet of CERN open new and exciting possibilities for the development of accelerator and storage ring high-field dipole magnets in the 10 T range with stored energies of 1 MJ per metre of length.