MC5: Beam Dynamics and EM Fields
D12: Electron Cloud and Trapped Ion Effects
Paper Title Page
MOPOST049 Electron Cloud Build-Up for the Arc Sextupole Sections of the FCC-ee 191
 
  • J.E. Rocha Muñoz, G.H.I. Maury Cuna
    Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
  • K.B. Cantún-Ávila
    UADY, Mérida, Yucatán, Mexico
  • F. Zimmermann
    CERN, Meyrin, Switzerland
 
  Funding: Consejo Nacional de Ciencia y Tecnología (CONACyT) - México
In particle accelerators that operate with positrons, an electron cloud may occur due to several mechanisms. This work reports preliminary studies on electron cloud build-up for the arc sextupole sections of the positron ring of the FCCe+e using the code PyECLOUD. We compute the electron cloud evolution while varying strategic parameters and consider three simulation scenarios. We report the values of the central density just before the bunch passage, which is related to the single-bunch instability threshold and the electron density threshold for the three scenarios. In addition, we compare the simulated electron distribution across the central circular cross-section for a chamber with and without winglets.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST049  
About • Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 25 June 2022
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WEIZSP2 Trapping of Neutral Molecules by the Electromagnetic Beam Field 1649
 
  • G. Franchetti
    GSI, Darmstadt, Germany
  • F. Zimmermann
    CERN, Meyrin, Switzerland
 
  Neutral uncharged molecules are affected by the electromagnetic field of a charged particle beam if they carry either an electric or a magnetic dipole moment. The residual gas in an accelerator beam pipe consists of such molecules. In this paper we study their dynamics. Under a few approximations, whose validity we explore and justify, we derive the equations of motion of neutral molecules and their invariants, determine the conditions for these neutral molecules to become trapped in the field of the beams as function of beam-pipe temperature, and compute the resulting enhancement of molecule density in the vicinity of the beam. We demonstrate that large agglomerates of molecules, "flakes," are much more likely to be pulled into the beam than single molecules, and suggest that this phenomenon might help explain some beam observations at the Large Hadron Collider.  
slides icon Slides WEIZSP2 [6.142 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEIZSP2  
About • Received ※ 07 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 22 June 2022
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