1. Preliminary Simulation on Electron Cloud Build-up in SppC Liu Yu Dong

2. Content The 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

3. The Photon simulations For SPPC, a proton can produce photons 2236, E crit =3.89keV

4. Photon Reflectivity (R) R can be calculated and measured as a function of Material, Angle of incidence  Photon energy, and Surface Roughness (best in the low regime).

5. 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

6. 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).)

7. 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

8. x-distribution of electrons in chamber

9. Preliminary Simulation on bulid-up of electron in SppC ( By Code ECIC developed by Liu Yu Dong for BEPCII) ParametersValue Bunch particles n b (10 11 )2.0 Bunch spacing (ns)25 Pipe radius (mm)20 Circumference(km)54.7 Tune60.3 rms bunch length(75mm)75.5 Bunch size (rm)1/1 Dipole magnetic field (T)20 Quadrupole(T/m 2 )1000 Simulation parameters

10. Electron Cloud in Drift Region

11. Electron Cloud in Dipole Magnetic Field

12. Electron Cloud in Quadrupole Magnetic Field

13. 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.

14. Thank you for attention!