SUPERCONDUCTING CAVITIES FOR ACCELERATORS

Superconducting cavities have been in operation in accelerators for 25 years. In the last decade many installations in storage rings and lin acs have been completed. Meanwhile, nearly 1 km of active cavity lengt h is in operation in accelerators. Large-scale applications of superco nducting radiofrequency systems are planned for future e(+)e(-) linear colliders and proton linacs. Superconducting cavities have been prove d to operate at higher gradient, lower AC power demand and more favour able beam dynamics conditions than comparable normal conducting resona tors. The performance of the best single-cell cavities:comes close to the intrinsic limitation of the superconducting material. Complete mul ticell structures with all auxiliaries (couplers, tuner, etc) lag behi nd in performance because of their complexity. In this paper, an overv iew of accelerators with superconducting cavities is given. Limitation s of superconducting performance are described and research and develo pment efforts towards understanding and curing these effects are discu ssed in detail. Fundamentals of superconductivity and radiofrequency c avity design are briefly explained.