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e - cloud simulations (update)

e - cloud simulations (update). C.Octavio Dom ínguez , Giovanni R umolo, Frank Zimmermann. 11 h February 2011 - e - cloud simulations. C ontents. SPS simulations (2003) reproduction Method Partial conclusions 2) LHC simulations N b scan with higher seed pressure

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e - cloud simulations (update)

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  1. e- cloud simulations (update) C.Octavio Domínguez, Giovanni Rumolo, Frank Zimmermann 11hFebruary 2011 - e-cloudsimulations

  2. Contents • SPS simulations (2003) reproduction • Method • Partial conclusions • 2) LHC simulations • Nb scan with higher seed pressure • Parameter studies at the LHC IR3: State of the art 2 11hFebruary 2011 - e-cloudsimulations

  3. Contents • SPS simulations (2003) reproduction • Method • Partial conclusions • 2) LHC simulations • Nb scan with higher seed pressure • Parameter studies at the LHC IR3: State of the art 3 11hFebruary 2011 - e-cloudsimulations

  4. SPS simulations (2003) Goal: to reproduce this plot R? emax? 4 11hFebruary 2011 - e-cloudsimulations

  5. SPS simulations (2003) No agreement at the beginning (especially for 150 G)  Let’s try whit those plots: Parameters: sz=0.225 m; eNx=(1.66Nb + 1)mm 1 batch, 72 bunches, 25 ns e- cloud monitor P=9 nTorr R=0.3, 0.5, 0.7; emax= 230, 260 No agreement yet 5 11hFebruary 2011 - e-cloudsimulations

  6. SPS simulations (2003) 6 11hFebruary 2011 - e-cloudsimulations

  7. SPS simulations (2003) 7 11hFebruary 2011 - e-cloudsimulations

  8. SPS simulations (2003) 8 11hFebruary 2011 - e-cloudsimulations

  9. SPS simulations (2003) Neither with 4 batches It seems there were several sensitive changes in the code 9 11hFebruary 2011 - e-cloudsimulations

  10. SPS simulations (2003) Only 100 G simulations (No multipacting at 150 G!) 10 11hFebruary 2011 - e-cloudsimulations

  11. SPS simulations (2003) 11 11hFebruary 2011 - e-cloudsimulations

  12. SPS simulations (2003) • Conclusions • The code has suffered sensitive changes along these years mainly due to the correction (by G.Belodi) of the bug in the model for the angular dependence of dmax • “100% option” seems to agree slightly better with measurements (?) • We cannot simulate yet the measurements accurately enough • BUT: We see the stripes  We can trust our results  not enough seed pressure in the Nb scan study at the LHC arcs? Was the inter-bunch time step too “coarsy”? … 12 11hFebruary 2011 - e-cloudsimulations

  13. Contents • SPS simulations (2003) reproduction • Method • Partial conclusions • 2) LHC simulations • Nb scan with higher seed pressure • Parameter studies at the LHC IR3: State of the art 13 11hFebruary 2011 - e-cloudsimulations

  14. LCH arcs - Nb scan From 17/1/2011: P=1 nTorr; nisteps=400 No stripes!!! 14 11hFebruary 2011 - e-cloudsimulations

  15. LCH arcs - Nb scan • The Nb scan at the LHC arcs was repeated for 4 different cases: • - P=32 nTorr; 90% created e- in the beam volume • - P=320 nTorr; 90% created e- in the beam volume • - P=32 nTorr; 100% created e- in the beam volume • - P=32 nTorr; 100% created e- in the beam volume • For all cases: nbstep=200 and nistep=2500 (not so course; nistep(fine)=7462) • Other parameters used were: dmax=2.6, R=0.5, emax=230 eV 15 11hFebruary 2011 - e-cloudsimulations

  16. LCH arcs - Nb scan For 100% of the e- generated in the beam volume no stripes at all!!!! 16 11hFebruary 2011 - e-cloudsimulations

  17. LCH arcs - Nb scan 17 11hFebruary 2011 - e-cloudsimulations

  18. LCH arcs - Nb scan 18 11hFebruary 2011 - e-cloudsimulations

  19. LCH arcs - Nb scan The pressure definitely has an impact on the stripes 19 11hFebruary 2011 - e-cloudsimulations

  20. LCH arcs - Nb scan Nb = 1.5·1011ppb 20 11hFebruary 2011 - e-cloudsimulations

  21. LCH arcs - Nb scan 21 11hFebruary 2011 - e-cloudsimulations

  22. LCH arcs - Nb scan Even if we don’t know the exact energy of the e- at which the effects in the walls start to be important, the scrubbing strategy shouldn’t depend on this parameter 22 11hFebruary 2011 - e-cloudsimulations

  23. LCH arcs - Nb scan • Conclusions • The stripes formation depends radically on the assumed • amount of e- created in the beam volume • Pressure shows also an effect in the position as well as in the • shape of the stripes • The scrubbing strategy should not depend on the energy • threshold for e- impinging the walls 23 11hFebruary 2011 - e-cloudsimulations

  24. Contents • SPS simulations (2003) reproduction • Method • Partial conclusions • 2) LHC simulations • Nb scan with higher seed pressure • Parameter studies at the LHC IR3: State of the art 24 11hFebruary 2011 - e-cloudsimulations

  25. LCH IR3 Measurement ECLOUD (from qlosswh.data) 25 11hFebruary 2011 - e-cloudsimulations

  26. LCH IR3 – Method allaD.Schulte 1 or 2 batches 2 different batch spacings Absolute flux Total # of e- # of with e- E>10eV 26 11hFebruary 2011 - e-cloudsimulations

  27. LCH IR3 27 11hFebruary 2011 - e-cloudsimulations

  28. LCH IR3 28 11hFebruary 2011 - e-cloudsimulations

  29. LCH IR3 29 11hFebruary 2011 - e-cloudsimulations

  30. LCH IR3 30 11hFebruary 2011 - e-cloudsimulations

  31. LCH IR3 31 11hFebruary 2011 - e-cloudsimulations

  32. LCH IR3 32 11hFebruary 2011 - e-cloudsimulations

  33. LCH IR3 33 11hFebruary 2011 - e-cloudsimulations

  34. LCH IR3 34 11hFebruary 2011 - e-cloudsimulations

  35. LCH IR3 35 11hFebruary 2011 - e-cloudsimulations

  36. LCH IR3 36 11hFebruary 2011 - e-cloudsimulations

  37. LCH IR3 37 11hFebruary 2011 - e-cloudsimulations

  38. LCH IR3 38 11hFebruary 2011 - e-cloudsimulations

  39. LCH IR3 39 11hFebruary 2011 - e-cloudsimulations

  40. LCH IR3 40 11hFebruary 2011 - e-cloudsimulations

  41. LCH IR3 41 11hFebruary 2011 - e-cloudsimulations

  42. LCH IR3 • Preliminary conclusions (maybe too optimistic?): • 2.1 < dmax < 2.3 • 0.4 < R < 0.7 • Work to do: • Identify better the interesting regions for each batch spacing • Make finer grids • Try to do simulations setting as seed pressure the value from the • measurement for each batch spacing • Cross the fingers and hope that we get a good agreement, . 42 11hFebruary 2011 - e-cloudsimulations

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