Higher-order mode analysis at the BNL Energy Recovery Linac

Johnson, E.C. ; Ben-Zvi, I. ; Hahn, H. ; Hammons, L. ; Xu, W.

Brookhaven National Laboratory

关键词: Copper;    Cavities;    43 Particle Accelerators;    Excitation;    Simulation;   

DOI  :  10.2172/1025507
RP-ID  :  BNL--96167-2011-IR
RP-ID  :  DE-AC02-98CH10886
RP-ID  :  1025507

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来源: UNT Digital Library

【 摘 要 】

Understanding the prevalence and structure of higher-order modes (HOMs) in accelerator cavities is critical because their excitation can result in problematic single bunch and multi-bunch effects. Particularly hazardous are dipole modes, which are more easily excited due to their linear field nature near the beam center. During a recent superconducting test on the energy recovery linac (ERL) cavity at Brookhaven National Laboratory (BNL), 8 of the highest-Q HOMs were measured for the first time. In conjunction with analysis of CST Microwave Studio simulation results for the ERL model, one of these modes was further studied in the copper prototype ERL cavity. A method of identifying HOMs utilizing existing holes drilled in copper cavity cells was developed and used to conclude that the observed high-Q mode was a quadrupole.