1. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 1/21 CLIC_DDS_HPA study 30.11.2010

2. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 2/21 CLIC_DDS Study Collaboration Vasim Khan Alessandro D’Elia Roger Jones Alexej Grudiev Germana Riddone Vadim Soldatov Walter Wuensch Riccardo Zennaro University of Manchester and Cockcroft institute, U.K. CERN, Switzerland

3. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 3/21 Outlook High Phase Advance (HPA) Structures: Merits and Demerits CLIC_DDS_HPA Future of CLIC_DDS_HPA

4. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 4/21 High Phase Advance Structures 1) Low group velocity → Less power absorbed during breakdown Ref: R.M. Jones, et. al., SLAC-PUB 8887 CLIC

5. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 5/21 NLC: Band partitioning NLC: DS1 a = 4.23 mm ψ acc : 120°→ 150°:Lowest dipole kick factor reduces by ~ 20% Ref: R.M. Jones, et. al., SLAC-PUB 9467

6. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 6/21 Fundamental mode Optimisation CLIC_DDS_HPA

7. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 7/21 Band partitioning: CLIC DDS_A and DDS_HPA

8. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 8/21 120deg. Γ x = 0.0126 Cell # 1 a=4.0 mm, t=4.0 mm 150deg. Γ x = 0.021 Cell # 1 a=4.0 mm, t=3.2 mm Dipole mode properties

9. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 9/21 DDS_HPA

10. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 10/21 RF parametersUnitDDS_ADDS_HPA42DDS_HPA32 Phase advance / cellDeg.120150 Iris thicknessmm4/1.473.2/2.8 Bunch population10 9 4.2 3.2 Q (In / Out)-5020 / 65346931/7045 R’ (In / Out)MΩ/m51 / 11872.4/102.4 vg/c (In / Out)%2.07 / 1.02.1 / 0.45 Eacc max (L./UnL.)MV/m105 / 13293.3/ 14390/ 138 P in MW7168.263.6 ∆T max sur oKoK51 48 E max sur MV/m220234225 S c max W/μm 2 6.755.95.5 RF-beam efficiency%23.52923.3 Comparison: 120 vs 150

11. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 11/21 DDS_HPA: Merits and Demerits  Reduction in dipole bandwidth from 2.1 GHz to 1.8 GHz 1.Necessary to reduce bunch population to satisfy wakefield constrains 2.Luminosity reduction  Reduced input power  Less power absorbed during breakdown  Kick factors reduced  Better dipole coupling  Cost efficient ? MeritsDemerits

12. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 12/21 Enhanced damping: Eight manifolds Four regular and four additional manifolds Significant coupling

13. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 13/21 Cell parameters a = 4.3 mm t = 2.6 mm R c = 9.0 mm M r = 2.0 mm M c = 15.1 mm Fundamental mode properties Q=7080 R’/Q=10.356 (kΩ/m) v g =2.44 (%c) E s /E acc =2.22 H s /E acc =4.3 (mA/m) S c /E acc =5.45 x 10 -4 (W/μm 2 /Eacc 2 ) Dipole mode properties f syn =16.1 GHz Cell # 1

14. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 14/21 Cell parameters a = 2.5 mm t = 2.8 mm R c = 8.8 mm M r = 2.0 mm M c = 15.1 mm v g =0.32 (%c) Cell # 24 f syn =17.89 GHz

15. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 15/21 Lowest dipole mode properties Δf=2.25 σ=1.78 GHz Δf/f c = 10.5 (%c) Two Cell result Need improvement

16. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 16/21 Regular manifold Additional manifold Damping material εr=13 tanδ=0.02 NMr=2.8 Damp_r=1 Eight manifolds and Sic As the coupling in the last cell is poor it is important to enhance coupling by optimising the last cell

17. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 17/21 Cell # 24 :NMr=2.8 Damp_r=1.0

18. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 18/21 Accelerating mode NM r =2.8 Damp_r=1 ε r =14 tanδ=0.04

19. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 19/21 DDS_HPA_SiC SiC insertion in an 8-manifold cell improves damping The SiC properites and dimensions are optimised for Cell # 24 This optimisation does not improve damping of Cell # 1 Due to SiC losses, multiple avoided crossings are observed Need some modification in circuit model to incorporate additional losses (SiC) (future work ?)

20. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 20/21 Closing remarks CLIC_DDS_HPA: 1) Coupling looks promising 2) Need to improve bandwidth To be investigated in detail: 1) Eight manifolds 2) DDS_SiC damping 3) Circuit model modification to incorporate SiC losses

21. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 21/21 Acknowledgments We have benefited from discussions with Juwen Wang, Zhengai Li and Toshiyasu Higo on X-band structures Thanks to Igor Syratchev for suggesting to investigate CLIC_DDS_SiC. Thank you

22. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 22/21 Additional slides

23. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 23/21

24. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 24/21 Cell # 1 Cell # 24 Cell # 1 Cell parameters a = 4.6 mm t = 2 mm R c = 9.0 mm M r = 2.0 mm M c = 15.1 mm v g = 3.6 (%c) F syn ~15.76 GHz Cell # 24 Cell parameters a = 3.3 mm t = 3 mm R c = 9.0 mm M r = 2.0 mm M c = 15.1 mm v g = 0.95 (%c) F syn ~17 GHz Four manifolds

25. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 25/21 Cell # 1 Cell parameters a = 4.6 mm t = 2 mm R c = 9.0 mm M r = 2.0 mm M c = 15.1 mm v g = 3.6 (%c) F syn ~15.77 GHz

26. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 26/21 Cell # 24 Cell parameters a = 3.3 mm t = 3 mm R c = 9.0 mm M r = 2.0 mm M c = 15.1 mm v g = 0.95 (%c) F syn ~17 GHz

27. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 27/21 Cell # 1 Cell parameters a = 4.6 mm t = 2 mm R c = 9.0 mm M r = 2.0 mm M c = 15.1 mm v g = 3.6 (%c) F syn ~15.77 GHz

28. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 28/21 Cell # 24 Cell parameters a = 3.3 mm t = 3 mm R c = 9.0 mm M r = 2.0 mm M c = 15.1 mm v g = 0.95 (%c) F syn ~17 GHz

29. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 29/21 Cell # 1 :NMr=2.8 Damp_r=1.0

30. Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 30/21 Cell # 1 Cell parameters a = 4.6 mm t = 1 mm R c = 9.0 mm M r = 2.0 mm M c = 15.1 mm v g = 4.84 (%c) F syn ~15.65 GHz