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U.S. Department of Energy
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Measurements of Transverse Coupled-Bunch Instabilities in PEP-II

Technical Report ·
DOI:https://doi.org/10.2172/839845· OSTI ID:839845
At the design currents the PEP-II High and Low Energy Rings operate above the coupled-bunch instability thresholds in horizontal and vertical planes. Both machines have used analog bunch-by-bunch feedback systems to stabilize the beams since commissioning. Here we present a measurement technique that uses the capabilities of the PEP-II programmable digital longitudinal feedback system to provide transient diagnostics in X or Y directions. This technique allows one to measure instability growth or damping rates as well as oscillation frequencies in both open-loop and closed-loop conditions. Based on these measurements the configuration of the relevant transverse feedback channel can be optimized. The technique will be illustrated with instability measurements and feedback optimization examples. Comparisons of the measured modal patterns and growth rates to the theoretical predictions will be presented.
Research Organization:
Stanford Linear Accelerator Center (SLAC), Menlo Park, CA
Sponsoring Organization:
SC
DOE Contract Number:
AC02-76SF00515
OSTI ID:
839845
Report Number(s):
SLAC-PUB-11114
Country of Publication:
United States
Language:
English