Drive beam frequency multiplication system

1. Drive beam frequency multiplication system David Alesini, Caterina Biscari, Andrea Ghigo, Fabio Marcellini LNF-INFN CLIC08 Workshop – CERN – 14-17 October 08

2. DRIVE BEAM Basic Parameters

3. Beam temporal structure along the frequency multiplication system

4. From Hans Braun’s yesterday presentation 3 isochronous rings

5. Delay Loop • Total length : 241 nsec = 72.37 m • Only one passage • Isochronicity in half Loop • Trajectory length tunability - wiggler as in CTF3 • Normal conducting technology • (Bdipoles = 1.7 T) • Br = 8 Tm - r = 4.7 m • Total length of dipoles = 30 m • Dipoles with field index to eliminate defocusing quads • Rf deflector 500 MHz

6. CTF3 Delay Loop injection/extraction 2005

7. Injection-extraction DLcomparison CTF3 - CLIC THIN SEPTUM THICK SEPTUM

8. ADDING a Dquad between the rf deflector and the septum The odd and even bunches are separated and vertically focused on the septum position Dipole QF QD 5 ° Septum 101 mrad 14 mrad RF deflector 5 mrad 7.5 mrad 5.2cm 2.5 mrad SEPTUM position

9. CTF3 Combiner Ring Thick Septum Design based on TERA septa evolution from EPA design. Built by CIEMAT (Spain) 200 mrad @ 300 MeV

10. CTF3 Combiner Ring Thick Septum Parameters CLIC DL 800 < 25 30x80 1000

11. Dquad Septum Trajectory Tuning Wiggler Optical functions in half Delay Loop Qx = 5.1 Qy = 3.04

12. Combiner Ring 1 • Total length : 482 nsec =146 m • Up to three passages • Trajectory length tunability - 2 wigglers • Normal conducting technology • (Bdipoles = 1.7 T) • Br = 8 Tm - r = 4.7 m • Total length of dipoles = 30 m (as in Delay Loop) • Parallel poles Dipoles • Rf deflector 1 GHz • Design based on CTF3 Combiner Ring: • Isochronous arc with three dipoles

13. CLIC INJECTION or EXTRACTION Isochronous WIGGLER

14. Optical functions in half COMBINER RING 1 Qx = 22.2 Qy = 13.6

15. Combiner Ring 2 • Total length : 1450 nsec =434 m • Up to four passages • Trajectory length tunability • Normal conducting technology • (Bdipoles = 1.7 T) • Br = 8 Tm - r = 4.7 m • Total length of dipoles = 30 m • Parallel poles Dipoles • Rf deflector 3 GHz • Same arc of COMBINER RING 1 • Length filled with FODO cells

16. Optical functions in half COMBINER RING 2 Qx =38.1 Qy = 32.2

17. Main parameters of the 3 rings

18. Energy loss per turn (Synchrotron radiation) r = 4.7m 0.5 - 1.5 - 2.5 0 -1 0.5 -1.5 - 2.5 - 3.5 From 1 turn to 7 turns: energy loss from 0.6 to 4.2 MeV DE/E < 0.2 %

19. Correction of 2° order momentum compaction termscorrecting chromaticity to almost zero (To be tested with tracking- in progress)

20. LAYOUT of the three RINGS

21. RF deflectors

22. Combiner Ring 1: (recombination factor m = 3) f = nfbunch, n=1,2,4,5,… (but n≠m and its multiple integers) f = 1 GHz, 2 GHz, 4 GHz,… Same rule for CR2 (recombination factor m = 4): f = 3 GHz, 6 GHz,… Deflector Frequencies Delay Loop: f = flinac/2 (2n+1), n=0,1,2,… f = 0.5 GHz, 1.5 GHz, 2.5 GHz,…

23. (*) Standing Wave Deflectors A SW structure is already used for the CTF3 Delay Loop (*) β ~ 6 to reduce QL and filling time In CLIC the linac pulse (~ 140 μs) is generally much longer than the cavity filling time even in case of cavity with high loaded Q (that means higher efficiency structures). Only input coupling coefficient β=1 are considered  no reflected power from the cavity (excepted the RF pulse transients)  minimization of the klystron power

24. Delay Loop Standing Wave RF deflectorbeam energy: 2.38MeVdeflection: 5mrads

25. Combiner Ring 1 Standing Wave RF deflectorbeam energy: 2.38MeVdeflection: 5mrads

26. Combiner Ring 2 Standing Wave RF deflectorbeam energy: 2.38MeVdeflection: 5mrads

27. TW RF DEFLECTORS

28. DELAY LOOP

29. COMB RING 1

30. COMB RING 2