Author: Schulte, M.J.
Paper Title Page
WEPPP078 Status of the Mixed-signal Active Feedback Damper System for Controlling Electron-proton Instabilities for the Spallation Neutron Source 2894
  • Z.P. Xie, M.J. Schulte
    UW-Madison, Madison, Wisconsin, USA
  • C. Deibele
    ORNL, Oak Ridge, Tennessee, USA
  Funding: Work supported by Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy
As the beam intensity at the Spallation Neutron Source (SNS) in Oak Ridge National Laboratory (ORNL) is leveled up, it becomes necessary to have greater control over the electron-proton (e-p) instability. This paper presents an updated design of a mixed-signal transverse feedback system for active damping of the e-p instability. It describes the design, features and results of this feedback damper and reviews several experimental studies to understand the system performance and its limitations. The updated mixed-signal feedback damper system employs power amplifiers (PAs), analog-to-digital converters (ADCs), multiple field programmable gate array (FPGA) chips, and digital-to-analog converters (DACs) to provide feedback damping and system monitoring. Unlike existing analog damping systems, FPGA-based feedback damping systems offer programmability while maintaining high performance. The system gain, delay and digital signal processing components can be programmed during the fly to perform timing adjustments, correct for ring harmonics, and equalize magnitude and phase dispersions.