Superconducting Radiofrequency Technology for Accelerators

9 Pursuit of Higher Performance with Alternate Materials

Since the best Nb cavities with gradients of 45–50 MV/m (H_pk = 190–210 mT) approach the fundamental superheating field H_sh = 220 mT limit of the surface magnetic field, new materials with higher superheating field will eventually need to enter the picture in the quest for ever higher gradients and Q's. The development time for full-scale cavities with new materials is likely to be very long (decades). Hence it is important to explore new material avenues as early as possible. Many institutions are engaged in a variety of efforts, some of which we will cover in this chapter. At this stage, a single successful cavity that exceeds Nb performance in new materials is still far from realization. ...