Nb3Sn quadrupole magnets for the LHC IR

The development of insertion quadrupoles with 205 T/m gradient and 90 mm bore represents a promising strategy to achieve the ultimate luminosity goal of 2.5 × 10³⁴ cm^-2s^-1 at the Large Hadron Collider (LHC). At present, Nb₃Sn is the only practical conductor which can meet these requirements. Since Nb₃Sn is brittle, and considerably more strain sensitive than NbTi, the design concepts and fabrication techniques developed for NbTi magnets need to be modified appropriately. In addition, IR magnets must provide high field quality and operate reliably under severe radiation loads. The results of conceptual design studies addressing these issues are presented.