preliminary simulation on electron cloud build-up in sppc liu yu dong
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Preliminary Simulation on Electron Cloud Build-up in SppC
Liu Yu Dong
ContentThe Photon simulations
Reflectivity (R) and Photo-Electron Yield (PY)
First simulations of electron cloud build-up in FCC-hh
Preliminary Simulation on Bulid-up of Electron Cloud
in SppC
Electron cloud in Drift region
Electron cloud in Dipole and quadrupole magnetic field
The Photon simulations
Number of SR photons per proton per meter:
Critical energy of the SR spectrum:
For SPPC, a proton can produce photons 2236, Ecrit=3.89keV
Photon Reflectivity (R)
R can be calculated and measured as a function of Material,
Angle of incidence ,Q Photon energy, and Surface Roughness
(best in the low regime).
PY can only be measured and (being proportional to photo-absorption)
depends on the same parameters as R, plus the photoelectric cross-section
(that can be calculated) and the Surface condition (it is more surface
dependent).
Photo-electron Yield (PY)
R. CiminoFCC-hh Design Meeting 12-3-2015
The photoelectron yield and the photon reflectivity depend both on material and SR properties, so needs to be determined separately for each case• For 40eV SR (LHC), several experimental studies have been made
at/with CERN(V. Baglin et al, CERN-LHC-PROJECT-REPORT-206; V. V. Anashin et al, Nucl.
Instrum.Meth. A 448 (2000) 76.)• For 4keV SR (FCC), an experimental study was made at KEK• (Y. Suetsugu et al, Journal of Vacuum Science & Technology A 21, 186 (2003).)
First simulations of electron cloud build-up in FCC-hh (simulated by L. Mether, G. Iadarola, G. Rumolo with code PyECLOUD)
Simulations of build-up in typical arc elements:
Dipole, Quadrupole, Field-free region
Bunch patterns: 50b + 12e for 25ns spacing
x-distribution of electrons in chamber
Preliminary Simulation on bulid-up of electron in SppC
( By Code ECIC developed by Liu Yu Dong for BEPCII)
Parameters Value
Bunch particles nb(1011) 2.0
Bunch spacing (ns) 25
Pipe radius (mm) 20
Circumference(km) 54.7
Tune 60.3
rms bunch length(75mm) 75.5
Bunch size (rm) 1/1
Dipole magnetic field (T) 20
Quadrupole(T/m2) 1000
Simulation parameters
Electron Cloud in Drift Region
Electron Cloud in Dipole Magnetic Field
Electron Cloud in Quadrupole Magnetic Field
Conclusion and next plan for Electron Cloud
The photon reflectivity and photo-electron yield are
important characters for the distribution and density of
electron cloud;
The simulation results should be benchmarked with different
code;
The coating for vacuum pipe to reduce the SEY in magnetic
region is not necessary;
The dynamics of electrons in strong magnetic field need
more accurate physical model.
Thank you for attention!