Superconducting cavities for accelerators

Abstract

Superconducting cavities have been in operation in accelerators for 25 years. In the last decade many installations in storage rings and linacs have been completed. Meanwhile, nearly 1 km of active cavity length is in operation in accelerators. Large-scale applications of superconducting radiofrequency systems are planned for future e + e − linear colliders and proton linacs. Superconducting cavities have been proved to operate at higher gradient, lower AC power demand and more favourable beam dynamics conditions than comparable normal conducting resonators. The performance of the best single-cell cavities comes close to the intrinsic limitation of the superconducting material. Complete multicell structures with all auxiliaries (couplers, tuner, etc) lag behind in performance because of their complexity. In this paper, an overview of accelerators with superconducting cavities is given. Limitations of superconducting performance are described and research and development efforts towards understanding and curing these effects are discussed in detail. Fundamentals of superconductivity and radiofrequency cavity design are briefly explained.

High-power radio frequency pulse generation and extration based on wakefield excited by an intense charged particle beam in dielectric-loaded waveguides.

“…This traditional structure is designed with a smooth inner surface to avoid breakdown. Superconducting cavities have also been widely used to reduce power consumption (Proch 1998). One property of the disc-loaded accelerator is that it is not uniform in the longitudinal direction; therefore its cost is high due to complicated design, fabrication, tuning and assembly.…”

Gas cluster ion beam surface treatments for reducing field emission and breakdown of electrodes and SRF cavities

“…These 25-mm-diameter coupon samples were prepared using buffered chemical polishing (BCP), typically used for SRF cavities [15][16][17]. Field emission from the samples was studied using the Scanning Field Emission microscope (SFEM) located at the Surface Science Laboratory [18].…”

Superconductivity in high energy particle accelerators

“…For further reading the book RF Superconductivity for Particle Accelerators by H. Padamsee, J. Knobloch and T. Hays [23] and several review articles [24,25,26,27] are recommended.…”