Author: Lindberg, R.R.
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Overview of the APS-U Project  
  • R.R. Lindberg, A. Xiao
    ANL, Argonne, Illinois, USA
  This talk is about the overview of the APS-U Project.  
slides icon Slides MOP1WB02 [3.755 MB]  
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Theory of Longitudinal Multibunch Instabilities Including a Higher-Harmonic (Bunch-Lengthening) Cavity  
  • R.R. Lindberg
    ANL, Argonne, Illinois, USA
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The next generation of high-brightness storage rings typically require a higher-harmonic rf system to increase the bunch length and improve lifetime. The modified longitudinal dynamics has important implications for multi-bunch stability, since bunch lengthening also changes the synchrotron frequency both by lowering its mean (which reduces stability), and by increasing its variation with amplitude (which gives rise to Landau damping). To understand these competing effects, we present an analytic theory of longitudinal multi-bunch instabilities in the presence of a higher-harmonic cavity tuned to lengthen the bunch. The theory results in a relatively straightforward extension to the usual matrix-based multi-bunch analysis, and we show how the numerically determined growth rates can be used to understand the role of Landau damping. Finally, we compare predictions of the theoretical growth rates to those extracted from tracking simulations of the proposed APS Upgrade lattice.
slides icon Slides THP1WB03 [1.899 MB]  
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