On the feasibility of a tripler uprade for LHC

The design of high-field dipoles has been optimized using a block-coil geometry. The optimization includes stress management and flux plate suppression of multipoles from snap-back. The design has been extended to higher field by devising a hybrid coil geometry containing inner windings of Bi-2212 and outer windings of Nb$_{3}$Sn. A 24 Tesla dual dipole using this design offers the possibility of an LHC tripler. Issues of fabrication technology and synchrotron radiation control are discussed. There is no obvious upper limit to the field that could be attained for the dipoles of future hadron colliders.