Several future accelerator projects at Contoured Saddle Pad 30x30 Brookhaven for the Relativistic Heavy Ion Collider (RHIC) are based on energy recovery linacs (ERLs) with high-charge high-current electron beams.Their stable operation mandates effective higher-order-mode (HOM) damping.The development of HOM dampers for these projects is pursued actively at this laboratory.Strong HOM damping was experimentally demonstrated both at room and at superconducting (SC) temperatures in a prototype research and development (R&D) five-cell niobium superconducting rf (SRF) cavity with ferrite dampers.
Two room-temperature mock-up five-cell copper cavities were used to study various damper configurations with emphasis on capacitive antenna dampers.An innovative type of ferrite damper over a ceramic break for an R&D SRF electron gun also was developed.For future SRF linacs longer cryomodules comprised of multiple superconducting cavities with reasonably short intercavity transitions are planned.In such a configuration, the dampers, located closer to the cavities, will be at cryogenic temperatures; this will impose additional constraints and Cyclist Accessories - Helmets - Full Face complications.
This paper presents the results of simulations and measurements of several damper configurations.