A hybrid-coil Nb3Sn/Cu dipole is being developed for use in future hadron c
olliders, It features stress management within the coil, and the use of pur
e Cu strands within the coil to minimize the quantity of superconductor whi
le providing quench protection, A first 7 Tesla NbTi model of the design ha
s been built and will soon De tested.
Two designs for the first Nb3Sn model have been prepared. In one version, t
he placement of coil blocks and the inside contour of the steel flux return
are shaped to achieve collider-quality field over a 20:1 dynamic range of
operating field. In the other version, the fl;l return provides a close-cou
pled planar boundary that suppresses persistent-current multipoles by a fac
tor 20, and the same dynamic range is achieved using current programming of
the inner and outer coil elements, Both versions use the least superconduc
tor of any high-field collider dipole design.