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Steerenberg, R. R.

Paper Title Page
FRPMN074 Simulation Study of the Horizontal Head-Tail Instability Observed at Injection of the CERN Proton Synchrotron 4210
 
  • E. Metral, G. Rumolo, R. R. Steerenberg
    CERN, Geneva
  • B. Salvant
    EPFL, Lausanne
 
  For many years, a horizontal head-tail instability has been observed at the CERN Proton Synchrotron during the long 1.2 s injection flat-bottom. This slow instability has been damped using linear coupling only, i.e. with neither octupoles nor feedbacks. Using the nominal machine and beam parameters for LHC, the sixth head-tail mode number is usually observed. Several other modes were also observed in the past by tuning the chromaticity, and these observations were found to be in good agreement with Sacherer's formula. The purpose of this paper is to present the results of assessing the effect of chromaticity and linear coupling on this slow head-tail instability using the HEADTAIL simulation code, and to compare these simulations with both measurements performed over the last few years, and theoretical calculations.  
FRPMN076 Nominal LHC Beam Instability Observations in the CERN Proton Synchrotron 4222
 
  • R. R. Steerenberg, G. Arduini, E. Benedetto, A. Blas, W. Hofle, E. Metral, M. Morvillo, C. Rossi, G. Rumolo
    CERN, Geneva
 
  The nominal LHC beam has been produced successfully in the CERN Proton Synchrotron since 2003. However, after having restarted the CERN PS in spring 2006, the LHC beam was set-up and observed to be unstable on the 26 GeV/c extraction flat top. An intensive measurement campaign was made to understand the instability and to trace its source. This paper presents the observations, possible explanations and the necessary measures to be taken in order to avoid this instability in the future.