One of the goals that is pursued with the construction of superconductive undulators is to achieve comparatively high magnetic fields (1-2 T) on the axis of undulators with a short period (~10 mm). This leads to the generation of synchrotron radiation with a very short wavelength. The wavelength of the radiation emitted in an undulator is given by (formula).
The figure of merit for increasing the on axis magnetic field strength (for a given period length) in superconductive undulators is the achievable current density in the superconductor. A common conductor material for superconductive undulators is NbTi. An alternative is to use Nb3Sn, which can possibly achieve a critical current density twice as large as that of NbTi. However, Nb3Sn is quite brittle and its production and handling are more demanding than that of NbTi. Moreover the processing of the Nb3Sn wire has to be optimized for the range of magnetic field strength in which the wire is to be used. This R&D and optimization is the focus of the Nb3Sn project.