Outline

  1. Context
    Purpose of the study ;
  2. Design choices
    TMCI ; MI ; Mitigation ; dependencies.
  3. Ongoing
  4. News

Context

  • We are/were faced with several design choices for the booster :
    • Beam-pipe radius
    • Beam pipe material
    • Best momentum compaction factor
    • Best injection parameters
    • Damper or no damper
    • …

To guide our choices, we investigate single bunch and coupled bunch instabilities.

Design choices

See here for a more detailed presentation.

Beam pipe choices

Z-mode, 2.5e10 particles, 90 deg phase advance, 20 GeV

  • Let’s start with stainless steel ;
  • Now let’s increase its diameter ;

Bunch length variation as a function of the number of turns for a 25mm radius copper and stainless steel beam pipe.

Modes scan as a function of the pipe radius for the PA31.0 lattice (2023 baseline).

Lattice choices

PA31.0 vs PA31.3

  • PA31.0 (2023 baseline) ;
    • \(z/w~ \Rightarrow~\alpha_c=14.9~10^{-6}\) ;
    • \(h/t \bar{t}~ \Rightarrow~\alpha_c=7.34~10^{-6}\) ;
  • PA31.3 (2024 baseline) ;
    • \(\alpha_c=7.12~10^{-6}\) ;
    • \(R_p=30mm\) - Copper.

Modes scan as a function of the momentum compaction factor for the PA31.0 lattice (2023 baseline) with a copper beam pipe of \(R_p=25mm\) .

Modes scan as a function of the bunch population for the PA31.3 lattice (2024 baseline), \(\alpha_c=7.12~10^{-6}\) and a copper beam pipe of \(R_p=30mm\).

Lattices

PA31.3

  • Impedance margin
    • If we double the wake potential ;
  • TCBI growth rate
    • 8 \(\Rightarrow\) 310 turns ;

Modes scan as a function of bunch population for the PA31.3 baseline (2024), t ̄t operation and with a doubled wake-field contribution.

Transverse Growth rate as a function of the mode number for the PA31.3 baseline (2024), z operation, E =20 GeV, \(\sigma_z\) =4 mm, \(N_b\) = 15880, Cu beam pipe (R =25 mm).

Growth rate as a function of the mode number for the PA31.3 baseline (2024), z operation, E =20 GeV, \(\sigma_z\) =4 mm, \(N_b\) = 15880, Cu beam pipe (R =25 mm).

Take-away

  • Some other remaining questions :
    • What is the effect of the interplay between IBS, wakefield and synchrotron radiation ?
    • What is the effect of a jitter (including amplitude detuning) ?

Ongoing

  • XSuite migration
  • IBS studies
  • IBS/wake interplay
  • Jitter studies (with amplitude detuning)

Intrabeam scattering

PyHEADTAIL to XSuite migration

  • We took the opportunity of the migration to benchmark IBS against MadX for the booster ;
    • Very good agreement !
  • However, we still need to work on the linesegmentmap implementation for faster simulations.

Horizontal emittance evolution for the booster at 20 GeV, 4.5e10 particles. Comparison between XSuite and MadX.

Horizontal emittance evolution for the booster at 20 GeV, 4.5e10 particles. Comparison between XSuite (map) and MadX (lattice).

IBS/wake interplay

PyHEADTAIL to XSuite migration

  • Same here for the linesegmentmap ;
    • Non-physical transverse behaviour observed ;

Non physicalIBS/wakefield interplay for the booster at 20 GeV, 1.5e10 particles, using XSuite linesegmentmap.

Non physicalIBS/wakefield interplay for the booster at 20 GeV, 1.5e10 particles, using XSuite linesegmentmap.

News

  • MOU signed between CERN and GANIL ;
  • Looking for a postdoc to contribute to collective effects studies for the booster ;
  • HPC/HPDA resources secured for FCC-ee (CRIANN France) ;
    • Need support to set-up container environments ;
  • FUTURO project submitted by Barbara Dalena.

Thank you

Questions

FCC-ee accelerator design meeting
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