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Electron cloud build up in the FCC HEB Update on simulation results

Electron cloud build up in the FCC HEB Update on simulation results. L . Mether , G. Iadarola , G. Rumolo. FCC High Energy Booster (HEB). Envisaged additional injector, accelerating beam from SPS to FCC To be housed in current LHC or future FCC tunnel

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Electron cloud build up in the FCC HEB Update on simulation results

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  1. Electron cloud build up in the FCC HEBUpdate on simulation results L. Mether, G. Iadarola, G. Rumolo

  2. FCC High Energy Booster (HEB) • Envisaged additional injector, accelerating beam from SPS to FCC • To be housed in current LHC or future FCC tunnel • We study electron cloud build up in the FCC-tunnel HEB using PyECLOUD Electron cloud meeting

  3. Electron cloud simulations • We investigate the effect of beam pipe aperture and bunch spacing on the formation of e-cloud in HEB • Focus on arc dipoles, with beam at injection energy, 450 GeV • Consider circular beam pipe, scanning over aperture radii of 1.0 - 3.75 cm • Corresponding parameters: • Transverse emittancesεx ,εy : 2.5 µm • Beta functions βx ,βy : 67, 71 m Electron cloud meeting

  4. Electron cloud simulations • Since most machine details unknown, consider simple scenario: • Uniform initial distribution of seed electrons, no other primary electron production • Single uniform bunch train • Study 3 different bunch spacings • Bunch intensities scaled to keep average current constant Bunch spacing [ns] Intensity [ppb] Train length [b] • 5ns train shorter, results scaled accordingly Electron cloud meeting

  5. Simulation results Heat load as function of radius, 50 ns beam Heat load increases monotonically with R Electron cloud meeting

  6. Simulation results Heat load as function of radius, 25ns beam Heat load decreases for large R Electron cloud meeting

  7. Simulation results Heat load as function of radius, 5ns beam Heat load decreases with growing R, but oscillates Electron cloud meeting

  8. Simulation results Heat load as function of SEY, 50 ns beam Heat load increases monotonically with R Electron cloud meeting

  9. Simulation results Heat load as function of SEY, 25 ns beam Heat load decreases for large R Electron cloud meeting

  10. Simulation results Heat load as function of SEY, 5 ns beam Heat load decreases with growing R, but rises non-linearly Electron cloud meeting

  11. Simulation results - electron energy spectrum 50 ns • Peak energy of electrons impacting on the chamber wall, lies in the emitter region of SEY curve • For larger radius, peak closer to maximum SEY, δmax Electron cloud meeting

  12. Simulation results - electron energy spectrum 50 ns • Peak energy of electrons impacting on the chamber wall, lies in the emitter region of SEY curve • For larger radius, peak closer to maximum SEY, δmax Electron cloud meeting

  13. Simulation results - electron energy spectrum 50 ns • Peak energy of electrons impacting on the chamber wall, lies in the emitter region of SEY curve • For larger radius, peak closer to maximum SEY, δmax Electron cloud meeting

  14. Simulation results - electron energy spectrum 50 ns • Peak energy of electrons impacting on the chamber wall, lies in the emitter region of SEY curve • For larger radius, peak closer to maximum SEY, δmax Electron cloud meeting

  15. Simulation results - electron energy spectrum 50 ns • Peak energy of electrons impacting on the chamber wall, lies in the emitter region of SEY curve • For larger radius, peak closer to maximum SEY, δmax Electron cloud meeting

  16. Simulation results - electron energy spectrum 25 ns • Peak energy of electrons impacting on the chamber wall, still lies mainly in the emitter region of SEY curve • For larger radii, the peak moves towards lower energies, outside of the emitter region Electron cloud meeting

  17. Simulation results - electron energy spectrum 25 ns • Peak energy of electrons impacting on the chamber wall, still lies mainly in the emitter region of SEY curve • For larger radii, the peak moves towards lower energies, outside of the emitter region Electron cloud meeting

  18. Simulation results - electron energy spectrum 25 ns • Peak energy of electrons impacting on the chamber wall, still lies mainly in the emitter region of SEY curve • For larger radii, the peak moves towards lower energies, outside of the emitter region Electron cloud meeting

  19. Simulation results - electron energy spectrum 25 ns • Peak energy of electrons impacting on the chamber wall, still lies mainly in the emitter region of SEY curve • For larger radii, the peak moves towards lower energies, outside of the emitter region Electron cloud meeting

  20. Simulation results - electron energy spectrum 25 ns • Peak energy of electrons impacting on the chamber wall, still lies mainly in the emitter region of SEY curve • For larger radii, the peak moves towards lower energies, outside of the emitter region Electron cloud meeting

  21. Simulation results - electron energy spectrum 5 ns • For 5 ns beam, no clear energy peak • Electrons interact with several bunches before reaching chamber wall • Behavior very radius dependent in non-monotonic fashion Electron cloud meeting

  22. Simulation results - electron energy spectrum 5 ns • For 5 ns beam, no clear energy peak • Electrons interact with several bunches before reaching chamber wall • Behavior very radius dependent in non-monotonic fashion Electron cloud meeting

  23. Simulation results - electron energy spectrum 5 ns • For 5 ns beam, no clear energy peak • Electrons interact with several bunches before reaching chamber wall • Behavior very radius dependent in non-monotonic fashion Electron cloud meeting

  24. Simulation results - electron energy spectrum 5 ns • For 5 ns beam, no clear energy peak • Electrons interact with several bunches before reaching chamber wall • Behavior very radius dependent in non-monotonic fashion Electron cloud meeting

  25. Simulation results - electron energy spectrum 5 ns • For 5 ns beam, no clear energy peak • Electrons interact with several bunches before reaching chamber wall • Behavior very radius dependent in non-monotonic fashion Electron cloud meeting

  26. Simulation results - electron energy spectrum 5 ns • For 5 ns beam, no clear energy peak • Electrons interact with several bunches before reaching chamber wall • Behavior very radius dependent in non-monotonic fashion Electron cloud meeting

  27. Simulation results - electron energy spectrum 5 ns • For 5 ns beam, no clear energy peak • Electrons interact with several bunches before reaching chamber wall • Behavior very radius dependent in non-monotonic fashion Electron cloud meeting

  28. Simulation results - electron energy spectrum 5 ns • For 5 ns beam, no clear energy peak • Electrons interact with several bunches before reaching chamber wall • Behavior very radius dependent in non-monotonic fashion Electron cloud meeting

  29. Simulation results - electron energy spectrum 5 ns • For 5 ns beam, no clear energy peak • Electrons interact with several bunches before reaching chamber wall • Behavior very radius dependent in non-monotonic fashion Electron cloud meeting

  30. Simulation results - electron energy spectrum 5 ns • For 5 ns beam, no clear energy peak • Electrons interact with several bunches before reaching chamber wall • Behavior very radius dependent in non-monotonic fashion Electron cloud meeting

  31. Simulation results - electron energy spectrum 5 ns • For 5 ns beam, no clear energy peak • Electrons interact with several bunches before reaching chamber wall • Behavior very radius dependent in non-monotonic fashion Electron cloud meeting

  32. Simulation results - electron energy spectrum 5 ns • For 5 ns beam, no clear energy peak • Electrons interact with several bunches before reaching chamber wall • Behavior very radius dependent in non-monotonic fashion Electron cloud meeting

  33. Simulation results - electron energy spectrum 5 ns Electron cloud meeting

  34. Simulation results - electron energy spectrum 5 ns Electron cloud meeting

  35. Simulation results - electron energy spectrum 5 ns Electron cloud meeting

  36. Simulation results - electron energy spectrum 5 ns Electron cloud meeting

  37. Simulation results - electron energy spectrum 5 ns Electron cloud meeting

  38. Simulation results - electron energy spectrum 5 ns Electron cloud meeting

  39. Simulation results - electron energy spectrum 5 ns Electron cloud meeting

  40. Simulation results - electron energy spectrum 5 ns Electron cloud meeting

  41. Simulation results - electron energy spectrum 5 ns Electron cloud meeting

  42. Simulation results - electron energy spectrum 5 ns Electron cloud meeting

  43. Simulation results - electron energy spectrum 5 ns Electron cloud meeting

  44. Simulation results - electron energy spectrum 5 ns Electron cloud meeting

  45. Summary & conclusions • Electron cloud formation in the FCC HEB has been studied, varying chamber radius and bunch spacing • 50 ns beam • Larger radii produce more e-cloud, peak electron energy resides around δmax • 25 ns beam • e-cloud production grows with R until SEY-dependent threshold, where peak e-energy moves into absorber part of δ(E)curve • Cloud production then decreases as R grows further • 5 ns beam • Electrons interact with multiple successive bunches before hitting chamber wall more complex behavior • General trend is more e-cloud for smaller radii • For SEY ~ 1.2-1.5 very non-linear behavior Electron cloud meeting

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