1. A.Saini, K.Ranjan, N.Solyak, S.Mishra, V.Yakovlev on the behalf of our team Feb. 8, 2011 Study of failure effects of elements in beam transport line & its compensation. 6/9/2016 1

2. Outline Layout of SC CW lattice Study and compensation of effects of RF element’ s failure :- Failure of first cavity in SSR0 section. Failure of last cavity in SSR0 section. Failure of last cavity in SSR2 section. Study and compensation of effects of focusing element’s failure:- Failure of first solenoid in SSR0 section. Failure of first solenoid in SSR1 section. 6/9/2016 2

3. Goals of work Study the effects of failure of focusing & accelerating elements in beam transport line. Retuning of the lattice to compensate the effects of failed elements. To minimize beam losses (below 1W/m) & achieving smooth beam propagation through linac ( Beam envelope, emittance growth, halo growth are calculated & compared for each case ). Lattice version 3.8.3 is used for all calculations. \\tdserver1.fnal.gov\project\TD_SCRF\ProjectX\CW \650 MHz\Alex\v.3.8.3 6/9/2016 3

4. Initial Parameters Ensuring the surface field limit during retuning of amplitudes of rf cavities. - Maximum allowable surface magnetic field is 60 mT for spoke resonators (soft limitation in SSR sections). and 70 mT for elliptical cavities. Maximum field gradient ~ 10 T/ m in quad and <6 T/m in solenoids. 6/9/2016 4 Limitations & constraints Longitudinal emittance : 0.127  ∙mm mrad (changed to 0.275) Transverse emittance : 0.25 pi mm mrad. Initial Energy : 2.5 MeV * Tracewin code is used for all calculations (http://irfu.cea.fr/Sacm/logiciels/ )http://irfu.cea.fr/Sacm/logiciels/

5. Layout of Lattice 6/9/2016 5

6. Beam Envelope for ideal Lattice : No errors & failures  Calculation is performed with 10k macro-particles.  3 sigma Gaussian beam 6/9/2016 6

7. Emittance 6/9/2016 7 tt zz

8. Synchronous Phase Halo parameters 6/9/2016 8 HzHz HzHz HzHz

9. 9 Case 1: Failure of First cavity in SSR0 section SSR0 period MEBT elements available for re-tuning  Field amplitude and phases are re-adjusted in RF Cavity.  Magnetic field gradients are changed in solenoids and quads …

10. Failure of First cavity in SSR0 section Failed cavity 6/9/2016 10 1.045m 1.655m Gap between two successive RF element after failure of first cavity Gap between two successive RF elements

11. Beam Envelope 6/9/2016 11 Losses of Particles happen at these location

12. Emittance 6/9/2016 12

13. Compensation of Failed elements Solenoid Triplet RF Gaps SSR0 Cavity 6/9/2016 13  Matching section in MEBT & 3 following period in SSR0 section are used

14. Beam Envelope after retuning 6/9/2016 14

15. Emittance Before compensation After Compensation 6/9/2016 15

16. Halo Parameters Before compensation After Compensation 6/9/2016 16

17. Summary 6/9/2016 17 ParametersNo failure Failure of first Cavity SSR0 No Compensation Compensa tion At the end of Linac zz  ∙ mm mrad 0.180.740.21 tt  ∙ mm mrad 0.2580.270.255 Final Energy MeV 3028.323027.503028.45 Losses (%) -0.05-

18. 6/9/2016 18 Case 2: Failure of Last cavity in SSR0 section

19. Failure of Last cavity in SSR0 section 6/9/2016 19 Failed cavity 1.135m Note: Failed cavity is used for matching between sections

20. Beam Envelope 6/9/2016 20 Losses of Particles happen at these locations

21. Compensation of last cavity in SSR0 section 6/9/2016 21 Failed cavity Gap between two successive RF element after failure of last cavity 1.745m

22. Beam Envelope after compensation 6/9/2016 22

23. Emittance Before compensation After Compensation 6/9/2016 23

24. Halo Parameters Before compensation After Compensation 6/9/2016 24

25. Summary 6/9/2016 25 ParametersNo failure Failure of last Cavity SSR0 No CompensationCompensation At the end of Linac  z (  ∙ mm mrad) 0.180.480.19  t (  ∙ mm mrad) 0.2580.300.265 Final Energy (MeV) 3028.323025.133028.44 Losses (%) -0.02-

26. 6/9/2016 26 Case 3: Failure of Last cavity in SSR2 section

27. Beam Envelope Failure of last cavity in SSR2 section 6/9/2016 27 Failed cavity

28. Beam Envelope 6/9/2016 28

29. Compensation of failure of last cavity in SSR2 section 6/9/2016 29

30. Beam Envelope 6/9/2016 30

31. Emittance Before compensation After Compensation 6/9/2016 31

32. Summary 6/9/2016 32 ParametersNo failure Failure of last Cavity SSR2 No CompensationCompensation At the end of Linac  z (  mm mrad) 0.180.1940.19  t (  mm mrad) 0.2580.2670.255 Final Energy, MeV 3028.323020.003029.57 Losses, % ---

33. 6/9/2016 33 Case 4: Failure of first solenoid in SSR0 section

34. Beam Envelope Failure of first solenoid in SSR0 section 6/9/2016 34

35. Beam envelopes 6/9/2016 35

36. Compensation of Failure of first solenoid in SSR0 section 6/9/2016 36

37. Beam envelope 6/9/2016 37

38. Halo Parameters Before compensation After Compensation 6/9/2016 38

39. Beam Losses Before compensation After Compensation 6/9/2016 39

40. Emittance Before compensation After Compensation 6/9/2016 40

41. Summary 6/9/2016 41 ParametersNo failure Failure of first solenoid SSR0 No CompensationCompensation At the end of Linac  z (  mm mrad) 0.180.340.208  t (  mm mrad) 0.2581.70.262 Final Energy, MeV 3028.323028.313028.44 Losses -11.1 %-

42. 6/9/2016 42 Case 5: Failure of first solenoid in SSR1 section

43. Beam Envelope 6/9/2016 43

44. Beam Envelope before compensation 6/9/2016 44

45. Compensation of failure of first solenoid in SSR1 section 6/9/2016 45 Two solenoids - one upstream and one downstream are used for compensation

46. Beam Envelope after re-tuning 6/9/2016 46

47. Emittance Before compensation After Compensation 6/9/2016 47

48. Summary 6/9/2016 48 ParametersNo failure Failure of first solenoid SSR1 No Compensation Compensation At the end of Linac  z (pi mm mrad) 0.180.250.185  t (pi mm mrad) 0.2581.230.263 Final Energy, MeV 3028.323028.313028.43 Losses % ---

49. Conclusion Different scenario of failure of beamline elements are studied. In analysis the critical locations of failed elements are chosen to demonstrate strategy of tuning. It is possible to compensate the effects of failed elements by retuning neighboring elements ( RF cavity and Solenoids/Quads). 6/9/2016 49

50. Thank you 6/9/2016 50

51. SSR0 1 st cavity ViVfSynch Phase Initial Synch Phase Final elements 40266.424496.8Gap1 77150.257436.6Gap2 0.340.26645-44.00-41.5579SSR0_2 0.3510.333893-43.00-31.1175SSR0_3 GradiGrad felements 2.259682.1437Quad1 1.66269-1.71698Quad2 0.902310.97526Quad 3 2.484822.79846Sol 1 2.51923.13689sol2 4.109083.6261sol3 4.179964.65874sol4 4.252944.32889Sol5 6/9/2016 51

52. 6/9/2016 52