Measurements and Analysis of Longitudinal HOM Driven Coupled Bunch Modes in PEP-II Rings.

Fox, J. D. ; Winkle, D. V. ; Mastorides, T. ; Rivetta, C.

Technical Information Center Oak Ridge Tennessee

关键词: Accelerators PEP STORAGE RINGS;    BEAM DYNAMICS;    RF SYSTEMS;    DAMPING;   

RP-ID  :  DE2008934745

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

The growth rates of the longitudinal higher-order impedance-driven beam modes have greatly increased since the initial PEP-II design and commissioning. This increase is attributed to the addition of 6 1.2MW RF stations with 8 accelerating cavities in the HER and 2 1.2MW RF stations with 4 accelerating cavities in the LER, which allowed operations at twice the design current and almost four times the luminosity. As a result, the damping requirements for the longitudinal feedback have greatly increased since the design, and the feedback filters and control schemes have evolved during PEP-II operations. In this paper, growth and damping rate data for the higher-order mode (HOM) driven coupled-bunch modes are presented from various PEP-II runs and are compared with historical estimates during commissioning. The effect of noise in the feedback processing channel is also studied. Both the stability and performance limits of the system are analyzed.