Speaker
Dr
Makoto Tobiyama
(KEK Accelerator Laboratory)
Description
Transverse bunch-by-bunch feedback systems for curing coupled-bunch instabilities
have been working well since the early stages of the commissioning of the rings. To
meet requirments of 90 degrees of phase shift, suppression of the static component
and adjustable digital delay, a high-speed digital filter system with two-tap FIR
functionality has been developed. Beam diagnostic systems which are part of the
bunch feedback systems, such as bunch current monitors, betatron tune measurement
systems, and bunch oscillation recorders, have been playing important roles in the
tuning and understanding of the rings, enabling stable high-luminosity operation.
The performance of these systems is reported here. Recently, a decrease of the
luminosity with increase of the vertical feedback gain has been found. Possible
explanations, including the stability of the feedback systems and the effect of
residual noise, are also discussed.
Author
Dr
Makoto Tobiyama
(KEK Accelerator Laboratory)
