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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 - PowerPoint PPT Presentation
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Electron cloud build up in the FCC HEBUpdate on simulation results
L. Mether, G. Iadarola, G. Rumolo
Electron cloud meeting 2
FCC High Energy Booster (HEB)
27.6.2014
• 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 33
Electron cloud simulations
27.6.2014
• 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 radiiof 1.0 - 3.75 cm
• Corresponding parameters:• Transverse emittances εx ,εy : 2.5 µm
• Beta functions βx ,βy : 67, 71 m
Electron cloud meeting 44
Electron cloud simulations
27.6.2014
• 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
50 2 * 1011 325
25 1 * 1011 650
5 2 * 1010 1000
Bunch spacing [ns] Intensity [ppb] Train length [b]
5ns train shorter, results scaled accordingly
Electron cloud meeting 55
Simulation results
27.6.2014
Heat load as function of radius, 50 ns beam
Heat load increases monotonically with R
Electron cloud meeting 66
Simulation results
27.6.2014
Heat load as function of radius, 25 ns beam
Heat load decreases for large R
Electron cloud meeting 77
Simulation results
27.6.2014
Heat load as function of radius, 5 ns beam
Heat load decreases with growing R, but oscillates
Electron cloud meeting 88
Simulation results
27.6.2014
Heat load as function of SEY, 50 ns beam
Heat load increases monotonically with R
Electron cloud meeting 99
Simulation results
27.6.2014
Heat load as function of SEY, 25 ns beam
Heat load decreases for large R
Electron cloud meeting 1010
Simulation results
27.6.2014
Heat load as function of SEY, 5 ns beam
Heat load decreases with growing R, but rises non-linearly
Electron cloud meeting 1111
Simulation results - electron energy spectrum
27.6.2014
• 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
50 ns
Electron cloud meeting 1212
Simulation results - electron energy spectrum
27.6.2014
• Peak energy of electrons impacting on the chamber wall, lies in the emitter region of SEY curve
50 ns
• For larger radius, peak closer to maximum SEY, δmax
Electron cloud meeting 1313
Simulation results - electron energy spectrum
27.6.2014
• Peak energy of electrons impacting on the chamber wall, lies in the emitter region of SEY curve
50 ns
• For larger radius, peak closer to maximum SEY, δmax
Electron cloud meeting 1414
Simulation results - electron energy spectrum
27.6.2014
• Peak energy of electrons impacting on the chamber wall, lies in the emitter region of SEY curve
50 ns
• For larger radius, peak closer to maximum SEY, δmax
Electron cloud meeting 1515
Simulation results - electron energy spectrum
27.6.2014
• Peak energy of electrons impacting on the chamber wall, lies in the emitter region of SEY curve
50 ns
• For larger radius, peak closer to maximum SEY, δmax
Electron cloud meeting 1616
Simulation results - electron energy spectrum
27.6.2014
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 1717
Simulation results - electron energy spectrum
27.6.2014
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 1818
Simulation results - electron energy spectrum
27.6.2014
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 1919
Simulation results - electron energy spectrum
27.6.2014
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 2020
Simulation results - electron energy spectrum
27.6.2014
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 2121
Simulation results - electron energy spectrum
27.6.2014
• 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
5 ns
Electron cloud meeting 2222
Simulation results - electron energy spectrum
27.6.2014
• 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
5 ns
Electron cloud meeting 2323
Simulation results - electron energy spectrum
27.6.2014
• 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
5 ns
Electron cloud meeting 2424
Simulation results - electron energy spectrum
27.6.2014
• 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
5 ns
Electron cloud meeting 2525
Simulation results - electron energy spectrum
27.6.2014
• 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
5 ns
Electron cloud meeting 2626
Simulation results - electron energy spectrum
27.6.2014
• 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
5 ns
Electron cloud meeting 2727
Simulation results - electron energy spectrum
27.6.2014
• 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
5 ns
Electron cloud meeting 2828
Simulation results - electron energy spectrum
27.6.2014
• 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
5 ns
Electron cloud meeting 2929
Simulation results - electron energy spectrum
27.6.2014
• 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
5 ns
Electron cloud meeting 3030
Simulation results - electron energy spectrum
27.6.2014
• 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
5 ns
Electron cloud meeting 3131
Simulation results - electron energy spectrum
27.6.2014
• 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
5 ns
Electron cloud meeting 3232
Simulation results - electron energy spectrum
27.6.2014
• 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
5 ns
Electron cloud meeting 3333
Simulation results - electron energy spectrum
27.6.2014
5 ns
Electron cloud meeting 3434
Simulation results - electron energy spectrum
27.6.2014
5 ns
Electron cloud meeting 3535
Simulation results - electron energy spectrum
27.6.2014
5 ns
Electron cloud meeting 3636
Simulation results - electron energy spectrum
27.6.2014
5 ns
Electron cloud meeting 3737
Simulation results - electron energy spectrum
27.6.2014
5 ns
Electron cloud meeting 3838
Simulation results - electron energy spectrum
27.6.2014
5 ns
Electron cloud meeting 3939
Simulation results - electron energy spectrum
27.6.2014
5 ns
Electron cloud meeting 4040
Simulation results - electron energy spectrum
27.6.2014
5 ns
Electron cloud meeting 4141
Simulation results - electron energy spectrum
27.6.2014
5 ns
Electron cloud meeting 4242
Simulation results - electron energy spectrum
27.6.2014
5 ns
Electron cloud meeting 4343
Simulation results - electron energy spectrum
27.6.2014
5 ns
Electron cloud meeting 4444
Simulation results - electron energy spectrum
27.6.2014
5 ns
Electron cloud meeting 4545
Summary & conclusions
27.6.2014
• 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
