1. CLIC-away, 15/02/2006 M.Taborelli TS-MME CERN INFRASTRUCTURE FOR STRUCTURE TECHNOLOGY Mauro Taborelli

2. CLIC-away, 15/02/2006 M.Taborelli TS-MME Summary and aim: Where we are with materials properties and testing? Where do we want to go? Propose the steps in material testing and machining to produce a HDS resisting breakdown, to be inserted in CTF and sufficiently fatigue resistant for CLIC lifetime

3. CLIC-away, 15/02/2006 M.Taborelli TS-MME Present bi-metal choice for HDS: Mo and CuZr (C15000) Present knowledge: - interface strength almost as good as CuZr, with 25% failures - HIP of CuZr prevents and ideal thermal/mechanical treatment ➔ the elastic limit (60 MPa<300 MPa) and probably fatigue resistance cannot be easily optimized -can we make an HDS? does the joint resist machining? ( Trial ~ in the next 4 months) 4 HDS by end 2006 machining precision yes no improve joining method joint fails by machining

4. CLIC-away, 15/02/2006 M.Taborelli TS-MME Explosion bonding: -cold process: good for CuZr mech./fatigue properties -trials of 1-3 mm Mo/CuZr in Minsk: under inspection by metallurgy team -in flat geometry: needs to evaluate RF efficiency in an HDS -offer for trials from Finland (9 KEu) postponed after Minsk samples evaluation ➔ pull strength tests, hardness profiles (Coextrusion: -fragile interface in first trials (Lutch), no news since may(?)) Brazing: -soft soldering trials in house (in progress) -low temperature brazing (Torino) and simultaneous aging of CuZr (to be discussed) Mo Cu Other joining methods HIP joint fails Improve interface quality

5. CLIC-away, 15/02/2006 M.Taborelli TS-MME Present bi-metal choice for HDS: Mo and CuZr (C15000 Present knowledge: -pull strength: interface almost as good as CuZr, with 25% failures -HIP of CuZr prevents and ideal thermal/mechanical treatment ➔ the elastic limit (60 MPa<300 MPa) and probably fatigue resistance cannot be easily optimized -can we make an HDS? does the joint resist machining? ( Trial ~ in the next 4 months) 4 HDS by end 2006 machining precision yes no improve joining method joint fails by machining Is fatigue resistance sufficient for CLIC lifetime or requires improvement Treat/change material and/or joint Conditioning, breakdown rate

6. CLIC-away, 15/02/2006 M.Taborelli TS-MME Is it sufficient fatigue resistant for CLIC lifetime? How can we answer ? define a criterion with respect to experiments Critical roughness at 10 8 laser pulses Sonotrode survival at 10 11 excitations Critical roughness in high power RF experiment at 10 6 pulses ? ? ? a) Compare many materials in the 3 experiments and choose the best material b)Critical roughness means Ra<0.05 µm, below specifications for machining: we keep on the safe side CuZr “HIP” 1 m 30000 sh., T=240K

7. CLIC-away, 15/02/2006 M.Taborelli TS-MME -more CuZr-HIP samples (diamond turned) in laser irradiation - other materials (Glidcop®, CuCrZr?..) and treatments (shotless peening, CIP, explosion hardening) Therefore continue with: In laser irradiation at stress (T, H rf ) higher than nominal to get a measurable effect ➔ extrapolate stress limit at higher cycles number from (T)=const·N k ➔ if equation is the same for bulk, sonotrode can validate laser results at high cycle numbers ➔ proof with RF fatigue in Dubna (“few” cycles)

8. CLIC-away, 15/02/2006 M.Taborelli TS-MME Conditioning: - best treatment for Mo: annealing (800-1000C ) in UHV. not applicable on bi- metal part ➔ investigate sputtering (in progress) and e-beam “cleaning” - lower energy “pulses” (second system) Conditioning and breakdown rate: DC spark test Breakdown rate: -First trials based on previous experiment, improved version will follow Other materials: Glidcop, for fatigue regions,Cr, MoRe,….. Mo, annealed Saturation=435 MV/m Operation 410 MV/m Mo

9. CLIC-away, 15/02/2006 M.Taborelli TS-MME -At present +/- 15-20 μm on OFE-Cu, Ra=0.1-0.2 μm -no facilities at CERN (to change =1Mio/machine) HDS60 160 mm Accuracy we can get from various techniques: -milling (high speed*): - various firms at same level, possibly down to +/- 5 μm, R a =0.1-0.2 μm on OFE-Cu on existing machines, parts exist at +/- 3 μm -more difficult on Mo (R a =1 μm up to now) -one firm sells machines with precision on workpiece of +/-1 μm, Ra=0.1 μm (steel), up to 160000 rpm ➔ more HDS testpieces High precision machining: * milling as applied up to now was not HSM: tiny size of the tool needs faster spindle > 60000 rpm

10. CLIC-away, 15/02/2006 M.Taborelli TS-MME -EDM : cracks, dirty surface, needs development -ECM : +/-20μm, (possibly 5 μm after development) -elliptical vibration milling: +/-5μm generally used for diamond tools (incompatible with Mo) -e-beam for smoothing: to be tried first in spark test Other techniques and developments: 100 m Still to be considered: strategy of assembly of 4 quadrants (tech. student TS in march), prototypes of assembly…

11. CLIC-away, 15/02/2006 M.Taborelli TS-MME Needs: - control the shape of HDS with an accuracy of +/- 1μm and the the assembly of the 4 quadrants at +/- 2μm accuracy In house (TS-MME metrology lab): -measure profiles with +/- 3μm accuracy, in contact with 0.1N force (this leaves traces of 2 μm depth on soft copper) -no facilities “on the shelf” to assist/support HDS assembly: development must be made depending on assembly strategy Not sufficient for final accuracy Metrology 1: needs and CERN resources

12. CLIC-away, 15/02/2006 M.Taborelli TS-MME Higher accuracy available (~ 1.5 KF/control of 1 HDS): CTDEC (F): profiles in contact with an accuracy of 0.8 µm +(L[mm]/800) µm; applied force 0.1 N MIKES (Fin): profiles in contact with accuracy of 0.3 µm +(L[mm]/1000) µm; applied force 0.03N METAS (Ch): ISARA machine, profiles in contact with accuracy of +/- 0.030 µm; applied force < 0.1 mN, but limited measuring volume, less than an HDS; 2 prototypes existing Metrology 2: outside CERN ➔ we can consider that the technology is available ISARA- IBS contact 3D measurement: 30 nm volume accuracy, range 100 x 100 x 40 mm 3, 2 prototypes Invar frame interferometer xyz table Zerodur ref. table

13. CLIC-away, 15/02/2006 M.Taborelli TS-MME All these techniques - give a profile, no global view of the surface - are rather slow, but comparable with machining time (hours) No possibility for a global view at 1 μm accuracy, but… : -photogrammetry, 10 μm (possibly developed to 5 μm), limited by wavelength of light and very shiny surfaces -data export to HFSS through a CAD software is possible Tests at firms foreseen (together with TS-SU) Metrology 3: global view of parts

14. CLIC-away, 15/02/2006 M.Taborelli TS-MME Resources: SEM, metallurgical/mechanical inspections: TS-MME-MM,METSO Laser: 1 fellow needed (AB-CLIC?) Spark: 1 fellow +1 technical student TS + new system (AB-CLIC) Machining: testpieces in several firms (about 4000 €/piece) Design: -1 summer student (FIN) for CATIA parametrization+ support of TS-CSE - 1 technical student ASP (Torino) for layout -1-1.5 TS-MME drawing office, multipurpose -1 TS technical student for tolerancing and/or assembly strategy

15. CLIC-away, 15/02/2006 M.Taborelli TS-MME Acknowledgments: G. Arnau-Izquierdo S.Calatroni A.Cherif J.M.Dalin D.Glaude G.Jesse S.Mathot P.Miauton H.Neupert J.Paro T.Ramsvik S.Sgobba TS-SU Accelerators and Beams department: CLIC-Study team