Superconducting intermediate-velocity cavity development for RIA

This paper discusses the design and development of two types of intermediate-velocity superconducting cavity and an associated cryomodule for the RIA driver linac. The two cavity types are a 115 MHz, /spl beta//sub GEOM/ = 0.15 quarter-wave resonant (QWR) cavity, and a 173 MHz, /spl beta//sub GEOM/ = 0.26 coaxial half-wave cavity. The useful velocity range of the two cavity types extends from 0.1 to 0.4 c. Both cavities are well-corrected for dipole and quadrupole asymmetries in the accelerating field. A cryomodule is being designed to incorporate a separate vacuum system for the cavity vacuum in order to provide a clean, low-particulate environment for the superconducting cavities. This will enable a higher degree of surface cleanliness than has previously been the case for TEM-type, drift-tube-loaded superconducting cavities. The status of prototype cavity and cryomodule construction are reported.