Fabrication and component testing results for a Nb$_3$Sn dipole magnet

At present, the maximum field achieved in accelerator R&D; dipoles is slightly over 10 T, with NbTi conductor at 1.8 K. Although Nb$_3$Sn has the potential to achieve much higher fields, none of the previous dipoles constructed from Nb$_3$Sn have broken the 10 T barrier. We report here on the construction of a dipole with high current density Nb$_3$Sn with a predicted short sample limit of 13 T. A wind and react technique, followed by epoxy impregnation of the fiberglass insulated coils, was used. The problems identified with the use of Nb$_3$Sn in earlier dipole magnets were investigated in a series of supplemental tests. This includes measurement of the degradation of Jc with transverse strain, cabling degradation, joint resistance measurements, and epoxy strength tests. In addition, coil assembly techniques were developed to ensure that adequate prestress could be applied without damaging the reacted Nb$_3$Sn cable. We report here the results of these tests and the construction status of this 50 mm bore dipole.