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Electron Cloud meeting 16-05-2014

Simulation of EC detectors: implementation and results A. Romano, G. Iadarola , G. Rumolo Many thanks to: Christina Yin Vallgren. Electron Cloud meeting 16-05-2014. Outline. Introduction Simulation of EC detectors in PyECLOUD First results for SPS like strip monitor

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Electron Cloud meeting 16-05-2014

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  1. Simulation of EC detectors: implementation and resultsA. Romano, G. Iadarola, G. RumoloMany thanks to: Christina Yin Vallgren Electron Cloud meeting 16-05-2014

  2. Outline • Introduction • Simulation of EC detectors in PyECLOUD • First results for SPS like strip monitor • Comparison against previous ECLOUD simulations • Summary and future Work

  3. Outline • Introduction • Simulation of EC detectors in PyECLOUD • First results for SPS like strip monitor • Comparison against previous ECLOUD simulations • Summary and future Work

  4. New PS EC Detector New electron cloud (EC) detectors have been installed in one of the PS main magnets to study EC effects in strong magnetic field conditions (B>1 T) Grid Biased Electrode: Measure current from EC [By Teddy Capelli EN/MME]

  5. EC Detector EC detectors are used to measure the electron flux onto the chamber’s wall Electrons are collected by a shielded electrode and measured as a current signal Many thanks to M.Taborelli I_ ec e- V_bias

  6. EC Detector: effect of the magnetic field In a drift space (B=0) electrons are free to move inside the chamber. In a strong dipolar magnetic field, the electrons move along helicoidal trajectories around the field lines. Inside the hole there is no multipactor effect, electrons come only from the edge B

  7. Outline • Introduction • Simulation of EC detectors in PyECLOUD • First results for SPS like strip monitor • Comparison against previous ECLOUD simulations • Summary and future Work

  8. Simulation method development • For the development we considered the EC detector installed in the SPS (strip detector) since we can compare against previous simulations and measurements (also with applied B)

  9. Simulation method development • For the development we considered the EC detector installed in the SPS (strip detector) since we can compare against previous simulations and measurements (also with applied B) • 64 rows of holes shifted with respect to each other to explore different horizontal positions

  10. Simulation strategy What we have done ? • Due to the symmetric and periodic geometry of detector, it is possible to calculate the total current considering only 7 different rows • Each row has a different position of the holes on the top wall of the beam pipe • The surface of beam pipe is made of adjacent segments of different size and SEY: x z

  11. Simulation strategy What we have done ? • Due to the symmetric and periodic geometry of detector, it is possible to calculate the total current considering only 7 different rows • Each row has a different position of the holes on the top wall of the beam pipe • The surface of beam pipe is made of adjacent segments of different size and SEY: x z

  12. Simulation strategy What we have done ? • Due to the symmetric and periodic geometry of detector, it is possible to calculate the total current considering only 7 different rows • Each row has a different position of the holes on the top wall of the beam pipe • The surface of beam pipe is made of adjacent segments of different size and SEY: x z

  13. Simulation strategy What we have done ? • Due to the symmetric and periodic geometry of detector, it is possible to calculate the total current considering only 7 different rows • Each row has a different position of the holes on the top wall of the beam pipe • The surface of beam pipe is made of adjacent segments of different size and SEY: x z

  14. Simulation strategy What we have done ? • Due to the symmetric and periodic geometry of detector, it is possible to calculate the total current considering only 7 different rows • Each row has a different position of the holes on the top wall of the beam pipe • The surface of beam pipe is made of adjacent segments of different size and SEY: x z

  15. Simulation strategy What we have done ? • Due to the symmetric and periodic geometry of detector, it is possible to calculate the total current considering only 7 different rows • Each row has a different position of the holes on the top wall of the beam pipe • The surface of beam pipe is made of adjacent segments of different size and SEY: x z

  16. Simulation strategy What we have done ? • Due to the symmetric and periodic geometry of detector, it is possible to calculate the total current considering only 7 different rows • Each row has a different position of the holes on the top wall of the beam pipe • The surface of beam pipe is made of adjacent segments of different size and SEY: x z

  17. Simulation results …… what are the results? Hole Effect of the magnetic field on the EC distribution For B > 400 G the distribution stays practically constant

  18. Simulation results …… what are the results? For large B the hole gets depleted Effect of the magnetic field on the EC distribution For B > 400 G the distribution stays practically constant

  19. Simulation results Similar results for the different arrays of hole(through the chamber)

  20. Simulation results Similar results for the different arrays of holes(through the chamber)

  21. Simulation results Similar results for the different arrays of holes(through the chamber)

  22. Simulation results Similar results for the different arrays of holes(through the chamber)

  23. Simulation results • Similar results for the different arrays of holes(through the chamber)

  24. Simulation results • Similar results for the different arrays of holes(through the chamber)

  25. Simulation results • Similar results for the different arrays of holes(through the chamber)

  26. Simulations Comparison • The total currents (through the holes) for the different configurations look very similar • Small differences for intermediate B values I [uA] Aver. SEY=1.4

  27. Simulations Comparison SEY=1.4 Total current calculated considering the 64 rows of the detector

  28. Simulation results • Effect of the presence of the holes on the multipacting threshold • B=0  Threshold influenced by the holes (holes weaken the EC) • B=1000 G  Threshold independent from the holes

  29. Simulation results Decreasing the number of holes the threshold converges to the unperturbed case

  30. Simulation results • Electron flux profile with and without the holes for strong B B = 0.1 T, SEY = 1.35 • EC is suppressed at the hole locations but gets enhanced elsewhere •  the effect could be related to the electron space charge

  31. Simulations Comparison Simulation results are compatible with results of previous studies Previous ECLOUD simulation results PyECLOUD simulations G. Rumolo, 2009

  32. Outline • Introduction • Simulation of EC detectors in PyECLOUD • First results for SPS like strip monitor • Comparison against previous ECLOUD simulations • Summary and future Work

  33. Summary and future work • The capability of simulating EC detectors has been implemented in PyECLOUD • First application  study of SPS strip detector • The presence of the holes in the chamber perturbs the EC distribution • For low B, leads to a significant increase of the multipacting threshold • For high B, results in no change in threshold but stronger multipacting between holes because of less space charge • Successful benchmark with existing ECLOUD simulations for an SPS strip detector • Results reproduce well previous simulation performed with ECLOUD • Next steps • Apply model to PS shielded pick up in SS98 and compare with 2011/2012 time resolved data • Apply model for the new PS ecloud detectors in MU98 and predict 2014 measurements

  34. Thanks for your attention!

  35. Simulations Comparison Mean value of current considering the first 7 rows, for different SEY.

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