1. CLIC Drive Beam Injector Design Update Shahin Sanaye Hajari 1.Institute For Research in Fundamental Sciences (IPM), Tehran, Iran 2.CERN, Geneva, Switzerland

2. Contents 1. Injector layout and the latest results 2. Optimisation of the magnetic chicane 3. Chicane and the injector overall performance 3.1 Satellite population 3.2 Beam loss at chicane 4.Fourth SHB

3. 1 Injector layout and the latest results 1 1 Injector layout and the latest results 1.1 Injector Layout

4. 1 Injector layout and the latest results 2 1 Injector layout and the latest results 1.2 Latest results ParametersCurrent valueTarget value Longitudinal RMS bunch length3 mm RMS energy spread0.530 MeV< 0.5 MeV Satellite population2.6%As less as possible Transverse Normalised emittance35 mm-mrad<100 mm-mrad Average solenoidal field530 gaussAs small as possible Beam loss at chicane: 4%

5. 2 Optimisation of the magnetic chicane 3 2 Optimisation of the magnetic chicane 2.1 Bunch compression

6. 2 Optimisation of the magnetic chicane 4 2 Optimisation of the magnetic chicane 2.1 Bunch compression

7. 2 Optimisation of the magnetic chicane 5 2 Optimisation of the magnetic chicane 2.1 Bunch compression Before chicane After chicane Bunch length reduction: ~ 20 %

8. 2 Optimisation of the magnetic chicane 6 2 Optimisation of the magnetic chicane 2.2 Transvers plane and chicane parameters ParameterValue Dipole field0.186 T Dipole length29.5 cm Drift length70 cm Bending angle18.5 o

9. 3 Chicane and the injector overall performance 7 3 Chicane and the injector overall performance 3.1 Satellite population At P1 At P2 At P3

10. 3 Chicane and the injector overall performance 7 3 Chicane and the injector overall performance 3.1 Satellite population At P1 At P2 At P3

11. 3 Chicane and the injector overall performance 8 3 Chicane and the injector overall performance 3.2 Bunch length and energy spread correlation 40 o off-crest 20 o off-crest After first accelerating structure (6 MeV)

12. 3 Chicane and the injector overall performance 9 3 Chicane and the injector overall performance 3.3 Beam loss at chicane

13. 4 Fourth SHB 10 4 Fourth SHB 4.1 Satellite reduction motivation ModelSatellite population CDR version4.9% Current model2.1% 4 SHB1.0% Satellite cleaning system Number of SHBSatellite population 1~14% 2~5% 3~2% 4~1%

14. 4 Fourth SHB 11 4 Fourth SHB 4.2 Sub-harmonic bunching system parameters Cavity Distance to next cavity Voltage SHB1255 (cm)13 (kV) SHB2145 (cm)25 (kV) SHB385 (cm)35 (kV) SHB450 (cm)50 (kV) Prebuncher20 (cm)45 (kV) CavityVoltage SHB115 (kV) SHB230 (kV) SHB345 (kV) Prebuncher60 (kV) 4SHB 3SHB

15. 5 Conclusion 12 5 Conclusion By optimising the magnetic chicane to act as a bunch compressor as well as phase space cleaner the allowed bunch length at the end of injector will be 20% longer. This results in:  Satellite population reduction  Beam loss reduction By using an additional SHB the Satellite population can be reduced to 1.0%.

16. Thanks for your attention.

17. TW Buncher: Beam Loss Reduction Buncher parameterValue 1.2 5.7 L(cm)147 P(MW)~20 Beam parameterValue 7.23 0.317 2.38

18. Options for the Solenoid Channel: Emittance Growth