ORNL RAD, Oak Ridge, Tennessee, USA
The transverse feedback system in the Accumulator Ring of the Spallation Neutron Source~(SNS) is intended to damp broadband (≈40-120~MHz), coherent betatron motion due to e-p interaction. The SNS feedback system is based on an analog delay-line model with some signal conditioning and tuning parameters implemented digitally. This system provides a simple setup with two primary knobs, phase and gain, as well as an equalizer. This simplicity comes at the cost of some flexibility normally found in a standard mode-by-mode design, namely mode-by-mode phase, and gain control. In this paper we discuss the design, tuning, evaluation, and operation of the SNS feedback damper, and discuss the tradeoffs implicit in the design of the system.
