Author: Di Monte, N.P.
Paper Title Page
WEPME056 Application of Z-transform to Noise Response Modeling of a Bunch-by-bunch Feedback System 3058
  • C. Yao, N.P. Di Monte, A.J. Scaminaci, H. Shang
    ANL, Argonne, USA
  Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-ACO2-O6CH11357.
The APS storage ring has an electron beam energy of 7 GeV and a single current of up to 16 mA. Transverse beam instability is corrected by a combination of chromatic correction and bunch-by-bunch feedback system. Noises produced in the pickup circuits is processed and transferred to the beam the same as a beam signal, which contributes to beam motion when the loops are closed. By analyzing the input data stream of the feedback system, one can passively obtain useful information, such as the tunes, loop stability, noise spectrum, etc. This approach has been reported by J. Klute and D. Teytelman. We implemented a passive and continuous tune monitoring process at the APS storage ring. In order to understand the underlying principle, we applied z-transform analysis to the noise-response model of a bunch-by-bunch feedback system. Our analysis shows a clear relationship between the spectrum of the noise response and the open-loop response of the beam. The noise-response model can also be applied to other areas, such as stability and noise analysis of a bunch-by-bunch feedback system. This report presents our analysis and some experimental data.