Author: Buffat, X.
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MOPGW078 Change of Beam Distribution Due to Decoherence in the Presence of Transverse Feedback 281
SUSPFO098   use link to see paper's listing under its alternate paper code  
 
  • S.V. Furuseth, X. Buffat
    CERN, Geneva, Switzerland
  • S.V. Furuseth
    EPFL, Lausanne, Switzerland
 
  The effect of Landau damping is often calculated based on a Gaussian beam distribution in all degrees of freedom. The stability of the beam is however strongly dependent on the details of the distribution. The present study focuses on the change of bunch distributions caused by the decoherence of the excitation driven by an external source of noise, in the presence of both amplitude detuning and a transverse feedback. Both multiparticle tracking simulations and theoretical models show a similar change of the distribution. The possible loss of Landau damping driven by this change is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW078  
About • paper received ※ 08 April 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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WEYYPLM3 First Results of the Compensation of the Beam-Beam Effect with DC Wires in the LHC 2262
 
  • G. Sterbini, D. Amorim, H. Bartosik, A. Bertarelli, R. Bruce, X. Buffat, F. Carra, L.R. Carver, G. Cattenoz, E. Effinger, S.D. Fartoukh, N. Fuster-Martínez, M. Gąsior, M. Gonzalez-Berges, A.A. Gorzawski, G.H. Hemelsoet, M. Hostettler, G. Iadarola, O.R. Jones, N. Karastathis, S. Kostoglou, I. Lamas Garcia, T.E. Levens, L.E. Medina Medrano, D. Mirarchi, J. Olexa, S. Papadopoulou, Y. Papaphilippou, D. Pellegrini, M. Pojer, L. Ponce, A. Poyet, S. Redaelli, A. Rossi, B. Salvachua, H. Schmickler, F. Schmidt, K. Skoufaris, M. Solfaroli, R. Tomás, G. Trad, D. Valuch, C. Xu, C. Zamantzas, P. Zisopoulos
    CERN, Geneva, Switzerland
  • D. Amorim
    Grenoble-INP Phelma, Grenoble, France
  • M. Fitterer, A. Valishev
    Fermilab, Batavia, Illinois, USA
  • D. Kaltchev
    TRIUMF, Vancouver, Canada
  • S. Kostoglou
    National Technical University of Athens, Zografou, Greece
  • A.E. Levichev
    BINP SB RAS, Novosibirsk, Russia
  • A. Poyet
    Université Grenoble Alpes, Grenoble, France
 
  The compensation of the long-range beam-beam interactions using DC wires is presently under study as an option for enhancing the machine performance in the frame of the High-Luminosity LHC project (HL-LHC). The original idea dates back more than 15 years. After the installation of four wire prototypes in the LHC in 2018, a successful experimental campaign was performed during the last months. The experimental setup and the main results are reported in this paper.  
slides icon Slides WEYYPLM3 [6.371 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLM3  
About • paper received ※ 06 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPTS044 Instability Latency in the LHC 3204
 
  • S.V. Furuseth, D. Amorim, S. A. Antipov, X. Buffat, N. Mounet, E. Métral, B. Salvant
    CERN, Geneva, Switzerland
  • S.V. Furuseth, T. Pieloni, C. Tambasco
    EPFL, Lausanne, Switzerland
 
  The Large Hadron Collider (LHC) has experienced multiple instabilities that occur between minutes and hours after the last modification of the machine settings. The existence of instabilities with high latency has been reproduced also in simulations. Dedicated experiments, injecting a controlled noise into the beam, have now been performed to discover the dependence of this latency on key parameters. The results seem compatible with a mechanism linked to a steady and slow modification of the transverse beam distribution leading to a loss of Landau damping.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS044  
About • paper received ※ 30 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPTS045 High-Performance Scheduling of Multi-Beam Multi-Bunch Simulations 3208
 
  • S.V. Furuseth, X. Buffat
    CERN, Geneva, Switzerland
  • S.V. Furuseth
    EPFL, Lausanne, Switzerland
 
  Coherent multi-bunch interactions through beam-beam forces or wake fields can cause severe impacts on the beams in circular colliders, if not well understood and countered for. COMBI is a parallel multiparticle tracking code developed to study such interactions. Its implementation greatly limits its efficiency when considering realistic configurations featuring effects with different computational requirements, such as the multi-bunch interaction through wake fields, beam-beam interactions, transverse feedback and lattice non-linearities. A new parallel scheduling method, pipelining the effects for each bunch, has greatly sped up the code. The new version of the code, COMBIp, is presented here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS045  
About • paper received ※ 06 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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