Superconducting Cavities for Proton and Ion Linacs

In the last decade, one of the most active areas in the applications of the superconducting rf (SRF) technology has been for the acceleration of ions to medium energy (∼1 GeV/amu) and high power. One such accelerator is under construction in the US while others are being proposed in the US, Japan, and Europe. These new facilities require SRF accelerating structures operating in a velocity region that has until recently been unexplored, and new types of structures optimized for the velocity range from ∼0.2 to ∼0.8 c have been developed. We will review the requirements imposed by such applications, the properties of the low- and intermediate-velocity structures which have been developed for them and the status of their development