MEASUREMENTS AND ANALYSIS OF LONGITUDINAL HOM DRIVEN COUPLED BUNCH MODES IN PEP-II RINGS

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 sta-tions 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 re-quirements for the longitudinal feedback have greatly in-creased since the design, and the feedback filters and con-trol 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 compare