1. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 1 CLIC Quadrupoles Th. Zickler CERN

2. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 2 Outlook Main Beam Quadrupoles (MBQ) –Requirements and constraints –Proposed quadrupole layout –Magnetic field calculations and characteristics –List of open issues –Next steps Final Focusing Quadrupole (FFQ) Conclusions

3. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 3 Main Beam Quadrupoles MBQ

4. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 4 MBQ Requirements and Constraints 2001 Main Beam quadrupoles per CLIC Linac High reliability, very robust design, low MTBF Beam energy increase requires variation of integrated field gradient in the range between 15 Tm/m and 370 Tm/m Aperture and field requirements –Magnetic length:between 350 and 1850 mm –Field gradient: 200 T/m –Aperture radius:4 mm Integrated pulsed H/V steering coils Baseline: 4 types of different length Alternative: several magnets of one type connected in series

5. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 5 Preliminary Magnetic Design Aperture radius:4.00 mm Integrated gradient: 70 (170, 270, 370 ) Tm/m Nominal gradient: 200 T/m Iron length:346 (846, 1346, 1846) mm Magnetic length:350 (850, 1350, 1850) mm Magnet width:< 200 mm Important: this layout is based on magnetic computations only; no mechanical analysis has been done so far! The dimensions are presently not validated!

6. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 6 MBQ Magnetic Field Calculations

7. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 7 MBQ Gradient Homogeneity Gradient homogeneity: Better than 4 * 10 -4 inside good-field-region (GFR) GFR radius: 2.5 mm

8. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 8 MBQ Corrector Field Homogeneity Dipole field homogeneity: Better than 4 * 10 -1 inside good-field-region (GFR) GFR on x-axis: ± 2.5 mm Strong sextupolar component (b 3 )

9. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 9 Open Issues Cooling circuit –Long term reliability –Actual proposal: indirect water cooled coils Current density: 3 A/mm 2 or more Limited space in coil window Heat dissipation into tunnel ? Cooling efficiency ? –Advanced insulation materials –Other options: Water cooled yoke Decreased power consumption to avoid water cooling Hybrid magnet (permanent magnets combined with coils)  Advanced coil design and cooling layout needed

10. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 10 Open Issues (cont.) Manufacturing and assembly tolerances –Small aperture High mechanical precision to achieve required filed quality Tight manufacturing and assembly tolerances –Long and slim structure Good mechanical stability Support structure –Mechanical error analysis to quantify: Manufacturing tolerances Assembly tolerances Alignment tolerances –Large series production  New manufacturing and assembly technologies required

11. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 11 Open Issues (cont.) Mechanical and thermal stability –Thermal expansion Influence on field quality (shift of magnetic center) Deformation of mechanical structure (stress) Displacement of magnet (transversal) –Cooling flow induced vibrations Amplitude and frequency Maximum allowed coolant velocity Defining flow rate and pressure drop –Stability of magnetic centre Iron saturation effects Hysteresis effects Mechanical deformation due to magnetic forces

12. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 12 Open Issues (cont.) Other important issues –Magnetic measurements How to measure field quality in small aperture quadrupole? Method and measurement equipment to be defined –Vacuum chamber integration Low conductivity due to small aperture Mechanical support Limited space in coil window –Corrector optimization Integrated pulsed (20 ms) H/V steering coils (2 mT) Requires laminated yokes Low field quality acceptable? Constant current distribution vs. corrector coils Influence on gradient quality and stability of magnetic center? Eddy currents in the vacuum chamber

13. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 13 Next Steps Detailed Studies addressing open issues –Advanced coil and cooling layout and possible options –Thermal 3D model –3D Magnetic field analysis –Mechanical error analysis –Advanced yoke manufacturing and assembly techniques –Corrector optimization –Magnet design proposal –Mechanical layout for module integration –Resources needed: 1 FTE*y (mechanical engineer + PhD or Fellow) –Costs: 70 kCHF (mainly for design office) –Delay: 1 year

14. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 14 Next Steps (cont.) Quadrupole mock-up –Design and build a quadrupole mock-up –Part of EuCARD – WP8.3 (Task 2) –Start in 2009 –Purpose of the mock-up: Simulate mechanical, thermal, and magnetic effects Model will not provide final magnetic field Investigate the performance of the stabilisation equipment –Resources needed: 2.2 FTE*y (mechanical engineer + PhD or Fellow) –Costs: 240 kCHF –Delay: 18 months

15. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 15 Next Steps (cont.) Quadrupole Prototype –Design and build full functional Quadrupole –Start: > 2010 ? –Purpose of the prototype: Validate design, manufacturing and assembly techniques Evaluate final field quality Study and validate magnetic measurement method Study vacuum chamber integration Study corrector coil performance –Resources needed: ~ 4 FTE*y (mechanical engineer + technical engineer + PhD or Fellow ) –Costs: > 500 kCHF –Delay: > 2 years

16. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 16 Final Focusing Quadrupole

17. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 17 Final Focusing Quadrupole All questions and problems related to the MBQ are also relevant or even more important for the FFG. In the past 10 years, many papers and proposals have been released on this topics. To begin with, a detailed literature research is required to gain full overview on this subject.

18. CLIC Stabilisation Day’08 18 th March 2008 Thomas Zickler AT/MCS/MNC/tz 18 Conclusions – A preliminary magnetic design for the CLIC MB quadrupoles has been presented – Open issues have been pointed out – Future studies needed addressing open issues – Mock-up required for stabilization studies – Prototype needed to verify magnetic design and to conclude study