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Franchetti, G.

Paper Title Page
MOPC003 Benchmarking of Simulation Codes Based on the Montague Resonance in the CERN Proton Synchrotron 330
 
  • I. Hofmann, G. Franchetti
    GSI, Darmstadt
  • J.F. Amundson, P. Spentzouris
    Fermilab, Batavia, Illinois
  • S.M. Cousineau, J.A. Holmes
    ORNL, Oak Ridge, Tennessee
  • M. Giovannozzi, E. Métral
    CERN, Geneva
  • F.W. Jones
    TRIUMF, Vancouver
  • A.U. Luccio
    BNL, Upton, Long Island, New York
  • S. Machida
    KEK, Ibaraki
  • J. Qiang, R.D. Ryne
    LBNL, Berkeley, California
 
  Experimental data on emittance exchange by the space charge driven ‘‘Montague resonance'' have been obtained at the CERN Proton Synchrotron in 2002-04 as a function of the working point. These data are used to advance the benchmarking of major simulation codes (ACCSIM, IMPACT, MICROMAP, ORBIT, SIMBAD, SIMPSONS, SYNERGIA) currently employed world-wide in the design or performance improvement of high intensity circular accelerators. In this paper we summarize the experimental findings and compare them with the first three steps of simulation results of the still progressing work.  
TPAT070 Intensity and Bunch-Shape Dependent Beam Loss Simulation for the SIS100 3807
 
  • G. Franchetti, I. Hofmann, A. Orzhekovskaya, P.J. Spiller
    GSI, Darmstadt
 
  We have studied the combined influence of magnet nonlinearities, space charge and bunch shapes consistent with different RF scenarios on the long-term loss in the planned SIS100 synchrotron of the FAIR project. The simulation is a 3D tracking with "frozen-in" space charge calculation employing the MICROMAP code. Comparing a one-harmonic RF scenario with an alternative double-harmonic scenario we find that for the same absolute beam loss roughly twice the number of particles can be stored in the double-RF system. Moreover, a barrier bucket RF scenario is found to be loss free. This is due to the fact that loss is caused here by space-charge induced periodic resonance crossing, which is absent for the strictly flat bunch profile of the barrier case.  
ROPB004 Effect of Lattice and Electron Distribution in Electron-Cloud Instability Simulations for the CERN SPS and LHC 387
 
  • E. Benedetto, E. Benedetto
    Politecnico di Torino, Torino
  • G. Arduini, F. Roncarolo, F. Zimmermann
    CERN, Geneva
  • B. Feng, A.F. Ghalam, T.C. Katsouleas
    USC, Los Angeles, California
  • G. Franchetti
    GSI, Darmstadt
  • K. Ohmi
    KEK, Ibaraki
  • G. Rumolo
    CELLS, Bellaterra (Cerdanyola del Vallès)
 
  Several simulation codes have been adapted so as to model the single-bunch electron-cloud instability including a realistic variation of the optical functions with longitudinal position. In addition, the electron cloud is typically not uniformly distributed around the ring, as frequently assumed, but it is mainly concentrated in certain regions with specific features, e.g., regions which give rise to strong multipacting or suffer from large synchrotron radiation flux. Particularly, electrons in a dipole magnet are forced to follow the vertical field lines and, depending on the bunch intensity, they may populate two vertical stripes, symmetrically located on either side of the beam. In this paper, we present simulation results for the CERN SPS and LHC, which can be compared with measurements or analytical predictions.  
FPAP013 Emittance Growth Caused by Electron Cloud Below the “Fast TMCI” Threshold: Numerical Noise or True Physics? 1344
 
  • E. Benedetto, E. Benedetto
    Politecnico di Torino, Torino
  • G. Franchetti
    GSI, Darmstadt
  • K. Ohmi
    KEK, Ibaraki
  • D. Schulte, F. Zimmermann
    CERN, Geneva
 
  Simulations show a persisting slow emittance growth for electron cloud densities below the threshold of the fast Transverse Mode Coupling type instability, which could prove important for proton beams with negligible radiation damping, such as in the LHC. We report on a variety of studies performed to quantify the contributions to the simulated emittance growth from numerical noise in the PIC module and from an artificial resonance excitation due to the finite number of kicks per turn applied for modeling the cloud-bunch interaction.