1 / 84

Laser-based Beam Diagnostics for the RAL Front End Test Stand

Laser-based Beam Diagnostics for the RAL Front End Test Stand. David Lee david.a.lee@imperial.ac.uk 28.01.2009. Outline. The Front End Test Stand (FETS) Beam diagnostics Beam profile measurements Non-intrusive beam diagnostics Laser-based H − diagnostics FETS laser profile monitor

kurt
Télécharger la présentation

Laser-based Beam Diagnostics for the RAL Front End Test Stand

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Laser-based Beam Diagnostics for the RAL Front End Test Stand David Lee david.a.lee@imperial.ac.uk 28.01.2009

  2. Outline • The Front End Test Stand (FETS) • Beam diagnostics • Beam profile measurements • Non-intrusive beam diagnostics • Laser-based H− diagnostics • FETS laser profile monitor • Conclusion Laser-based Beam Diagnostics for the RAL Front End Test Stand • 1

  3. The Front End Test Stand Laser-based Beam Diagnostics for the RAL Front End Test Stand • 2 David Lee • 28/01/2009

  4. The Front End Test Stand Beam dump and laser emittance measurementupstream (not shown) MEBT and chopper RFQ Magnetic LEBT H− ion source Laser profile monitor Laser-based Beam Diagnostics for the RAL Front End Test Stand • 3

  5. Neutrino Factory Laser-based Beam Diagnostics for the RAL Front End Test Stand • 4

  6. Neutrino Factory Laser-based Beam Diagnostics for the RAL Front End Test Stand • 4

  7. Status Laser-based Beam Diagnostics for the RAL Front End Test Stand • 5

  8. Status Laser-based Beam Diagnostics for the RAL Front End Test Stand • 5

  9. Status Laser-based Beam Diagnostics for the RAL Front End Test Stand • 5

  10. Status Laser-based Beam Diagnostics for the RAL Front End Test Stand • 5

  11. Beam Diagnostics Laser-based Beam Diagnostics for the RAL Front End Test Stand • 6 David Lee • 28/01/2009

  12. Beam Profile Measurements • Why are beam profile measurements of interest? • First half of the beam emittance • Gives information about the charge density • And so the beam’s self field / space charge • Will the beam fit through the beam pipe? • What is the beam halo like? • … • How are they typically done? • Scintillator • Wire scanner • … Laser-based Beam Diagnostics for the RAL Front End Test Stand • 7

  13. Non-intrusive diagnostics • Allows for online monitoring of the beam • Keeps users happy Laser-based Beam Diagnostics for the RAL Front End Test Stand • 8

  14. Non-intrusive diagnostics • Allows for online monitoring of the beam • Keeps users happy • Beam dynamics not affected by the instrument • Keeps accelerator group happy Residual gas ion energy analyser RGIE spectrum (beam potential distribution) depending on position of emittance scanner Ion source dl’ / dW [μA / (eV m)] 200V 0V Allison scanner in / out Beam dump 0V 0.406T 0.365T W / eV Laser-based Beam Diagnostics for the RAL Front End Test Stand • 8

  15. P46 Plastic Ruby Non-intrusive diagnostics • Allows for online monitoring of the beam • Keeps users happy • Beam dynamics not affected by the instrument • Prevents the beam from damaging the instrument • Keeps accelerator group happy Laser-based Beam Diagnostics for the RAL Front End Test Stand • 8

  16. Ionisation Cross Section Laser-based Beam Diagnostics for the RAL Front End Test Stand • 9

  17. Ionisation Cross Section Laser-based Beam Diagnostics for the RAL Front End Test Stand • 9

  18. To measure Beam profiles Longitudinal emittances use photo-detached electrons Laser-based H− diagnostics Laser-based Beam Diagnostics for the RAL Front End Test Stand • 10

  19. To measure Beam profiles Longitudinal emittances use photo-detached electrons Laser-based H− diagnostics Collect the detached electrons − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − Photo-ionise someof the H- ions Separate species usinga dipole magnet Laser-based Beam Diagnostics for the RAL Front End Test Stand • 10

  20. Laser-based H− diagnostics Collect the detached electrons − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − Photo-ionise someof the H- ions Separate species usinga dipole magnet Laser-based Beam Diagnostics for the RAL Front End Test Stand • 10

  21. Laser-based H− diagnostics Collect the detached electrons − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − Photo-ionise someof the H- ions Separate species usinga dipole magnet Laser-based Beam Diagnostics for the RAL Front End Test Stand • 10

  22. Laser-based H− diagnostics Collect the detached electrons − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − Photo-ionise someof the H- ions Separate species usinga dipole magnet Laser-based Beam Diagnostics for the RAL Front End Test Stand • 10

  23. Laser-based H− diagnostics Collect the detached electrons − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − Photo-ionise someof the H- ions Separate species usinga dipole magnet Laser-based Beam Diagnostics for the RAL Front End Test Stand • 10

  24. Laser-based H− diagnostics Collect the detached electrons − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − Photo-ionise someof the H- ions Separate species usinga dipole magnet Laser-based Beam Diagnostics for the RAL Front End Test Stand • 10

  25. To measure Transverse emittances use photo-ionised neutrals Laser-based H− diagnostics Laser-based Beam Diagnostics for the RAL Front End Test Stand • 11

  26. To measure Transverse emittances use photo-ionised neutrals − − − − − − − − − − − − − − − − Laser-based H− diagnostics Use a dipole to separate out the particles neutralised by residual gas interactions Laser-based Beam Diagnostics for the RAL Front End Test Stand • 11

  27. To measure Transverse emittances use photo-ionised neutrals − − − − − − − − Laser-based H− diagnostics − − − − − Photo-ionised neutrals Photo-ionise some of the H- ions in the dipole Residual gasneutrals Laser-based Beam Diagnostics for the RAL Front End Test Stand • 11

  28. To measure Transverse emittances use photo-ionised neutrals CCD − − − − − − − − Laser-based H− diagnostics − Image with scintillator and CCD − − − − Photo-ionised neutrals Photo-ionise some of the H- ions in the dipole Residual gasneutrals Laser-based Beam Diagnostics for the RAL Front End Test Stand • 11

  29. CCD − − − − − − − − Laser-based H− diagnostics − Image with scintillator and CCD − − − − Photo-ionised neutrals Photo-ionise some of the H- ions in the dipole Residual gasneutrals Laser-based Beam Diagnostics for the RAL Front End Test Stand • 11

  30. The Front End Test StandLaser Profile Monitor Laser-based Beam Diagnostics for the RAL Front End Test Stand • 12 David Lee • 28/01/2009

  31. The Benefit of Multiple (>2) Projections Laser-based Beam Diagnostics for the RAL Front End Test Stand • 13 David Lee • 28/01/2009

  32. The Benefit of Multiple (>2) Projections Laser-based Beam Diagnostics for the RAL Front End Test Stand • 13

  33. The Benefit of Multiple (>2) Projections Laser-based Beam Diagnostics for the RAL Front End Test Stand • 13

  34. The Benefit of Multiple (>2) Projections Laser-based Beam Diagnostics for the RAL Front End Test Stand • 13

  35. Laser-scanning setup • To get multiple projections, need to be able to pass laser through beam at variety of angles • To do this, use movable mirrors mounted in vacuum vessel Laser-based Beam Diagnostics for the RAL Front End Test Stand • 14

  36. Laser-scanning setup Laser-based Beam Diagnostics for the RAL Front End Test Stand • 15

  37. Laser-scanning setup Laser-based Beam Diagnostics for the RAL Front End Test Stand • 15

  38. Optics A simple, one lens setup will be used to begin with Laser-based Beam Diagnostics for the RAL Front End Test Stand • 16

  39. Optics Laser-based Beam Diagnostics for the RAL Front End Test Stand • 17

  40. The Detector Faraday Cup Electrons Magnet H−, H0 Copperacceleratingsheath Laser-based Beam Diagnostics for the RAL Front End Test Stand • 18

  41. The Detector • Constructed here in the workshop • Compact; the whole assembly is~80x100x250 mm Beamdirection Laser-based Beam Diagnostics for the RAL Front End Test Stand • 19

  42. Simulations • Detector’s E and B fields simulated using a electromagnetic finite element program • CST EM Studio • Particle tracking was performed by the General Particle Tracer package • Input distribution from a pepperpot correlated emittance measurement of the ion source Laser-based Beam Diagnostics for the RAL Front End Test Stand • 20

  43. Simulations Faraday Cup Magnet yoke Copperacceleratingsheath Laser-based Beam Diagnostics for the RAL Front End Test Stand • 21

  44. Dipole Field Map • To confirm the simulation results the dipole had its field (bending component; By) mapped Laser-based Beam Diagnostics for the RAL Front End Test Stand • 22

  45. Dipole Field Map Laser-based Beam Diagnostics for the RAL Front End Test Stand • 23

  46. Dipole Field Map Laser-based Beam Diagnostics for the RAL Front End Test Stand • 24

  47. Longitudinal Acceptance • Electrons from residual gas interactions form a background to our measurement • Problem made worse by proximity to ion source • 20 ml per minute of hydrogen gas • To reduce this background, the longitudinal acceptance of the detector can be reduced byintroducing an additional electrode Laser-based Beam Diagnostics for the RAL Front End Test Stand • 25

  48. Longitudinal Acceptance Laser-based Beam Diagnostics for the RAL Front End Test Stand • 26

  49. Longitudinal Acceptance Laser-based Beam Diagnostics for the RAL Front End Test Stand • 26

  50. Longitudinal Acceptance Laser-based Beam Diagnostics for the RAL Front End Test Stand • 26

More Related