Vacuum, Surfaces & Coatings Group Technology Department Glassy Carbon Tests at HiRadMat 14 March 2014 C. Garion2 Outline: Introduction Context: Transparent material Figure of merit New material development Glassy carbon properties Test set-up Configuration Instrumentation Expected behaviour Result analysis HiRadMat C. Garion CERN/TE/VSC

Vacuum, Surfaces & Coatings Group Technology Department C. Garion3 New material development for transparent UHV structures Material choice Transparency is related to: 14 March 2014 HiRadMat

Vacuum, Surfaces & Coatings Group Technology Department C. Garion4 New material development for transparent UHV structures – Figures of merit Temperature rise in transient regime: Thermal fatigue: Temperature rise in steady state: Mechanical Stability (buckling): Several figures of merit, characterizing the material, can be used depending on the final application. 14 March 2014 HiRadMat

Vacuum, Surfaces & Coatings Group Technology Department C. Garion5 New material development for transparent UHV structures Radiation length [cm]Young Modulus [Gpa] X0E 1/3 Beryllium Epoxy30-36 CFRE30~ Carbon2935 (GC)95 Carbon/Al (60/40) (short fibers, randomly oriented) 84 SiC Al2O AlLi Al97037 Ti L Figure of merit for thin vacuum chambers 14 March 2014 HiRadMat

Vacuum, Surfaces & Coatings Group Technology Department C. Garion6 New material development for transparent vacuum chambers Figure of merit of different materials, normalized w.r.t. beryllium 14 March 2014 HiRadMat

Vacuum, Surfaces & Coatings Group Technology Department C. Garion7 New material development for transparent vacuum chambers Photon absorption of different materials, compared to beryllium 14 March 2014 HiRadMat

Vacuum, Surfaces & Coatings Group Technology Department New material development for transparent vacuum chambers – Glassy carbon C. Garion8 Glassy carbon tube Glassy carbon (GC): Obtained by the pyrolysis at high temperature of a highly reticulated resin. Two grades have been considered. Grade K is obtained after a heat treatment at 1000 °C whereas 2200 °C is used for the grade G. Chemical analyses have been done by EDS. The material is composed of around 98 % (weight) of carbon and 2% of oxygen. 14 March 2014 HiRadMat

Vacuum, Surfaces & Coatings Group Technology Department New material development for transparent vacuum chambers – Glassy carbon C. Garion9 Mechanical properties: Stiffness: 4 points bending tests on plates equipped with strain gauges Young modulus and Poisson’s ratio Strength: 4 points bending tests on bars (avoid chips during cutting) Compression tests Weibull’s distribution Young Modulus [GPa] Poisson’s Coefficient Grade G32.4 ± Grade K32.5 ±10.17 Average strength [MPa] Standard deviation [MPa} Weibull shape parameter Weibull scale parameter [Mpa] Flexure Compression points bending test on plates Elastic properties 4 points bending test on rods Survival probability for the bending test 14 March 2014 HiRadMat

Vacuum, Surfaces & Coatings Group Technology Department New material development for transparent vacuum chambers – Glassy carbon C. Garion10 Fracture toughness: Notched bar under 4 points bending test: Sample Groove depth [mm] Force to failure [N] Bending stress [MPa] K Ic [MPa.m 1/2 ] CT specimen: test in preparation  Two methods will be used to determine the toughness: Maximum force for a given stress intensity factor or load decrease during crack propagation.  Crack growth test is also foreseen Notched bar CT specimen and crack propagation simulation 14 March 2014 HiRadMat

Vacuum, Surfaces & Coatings Group Technology Department New material development for transparent vacuum chambers – Glassy carbon C. Garion11 Transition to metallic parts: CusilABA inteface layer Glassy carbon Ceramic Soldering with intermediate ceramic part: Compatible thermal expansion Higher mechanical strength Preliminary tests on crucible: No failure Initial gaps to be adjusted to have a good flow of the solder GC crucible soldered with a copper ring 14 March 2014 HiRadMat

Vacuum, Surfaces & Coatings Group Technology Department New material development for transparent vacuum chambers – Glassy carbon C. Garion12 Outgassing rate: Unbaked material: Throughput method Grade K : high outgassing Grade G : low outgassing Baked material: Gas accumulation method Grade G : outgassing rate of 1.5E-13 mbar l s -1 cm -2 Outgassing curve of unbaked glassy carbon Outgassing of baked glassy carbon 14 March 2014 HiRadMat

Vacuum, Surfaces & Coatings Group Technology Department Test Set-up - Configuration 14 March 2014 C. Garion13 HiRadMat Particle typeprotons Pulse intensity (range)Intensity ramp and full intensity plateau No. bunchesUp to 288 Intensity/bunch1.7E11 Spot size2  0.5mm 2 (down to 0.1 mm 2 if possible) Number of pulses100 Integral intensity~ 2E15 SPS window Glassy carbon disc, 50<  <100 (tbc) Aluminium tube under vacuum or inert gas Exit windows

Vacuum, Surfaces & Coatings Group Technology Department Test Set-up - Instrumentation 14 March 2014 C. Garion14 HiRadMat Instrumentation foreseen during tests at Hiradmat: Fast camera Strain gauges if relevant Temperature sensors LDV

Vacuum, Surfaces & Coatings Group Technology Department Test Set-up – Expected behavior 14 March 2014 C. Garion15 HiRadMat 3 mm Peak energy deposition: 1.8 J/mm3 (one nominal LHC beam at beam dump entrance windows: 3.2E14 7 TeV)  0.9 mm

Vacuum, Surfaces & Coatings Group Technology Department Result analysis 14 March 2014 C. Garion16 HiRadMat Tests would be probably done (tbc) in the CERN metallurgy and vacuum laboratories. Following measurements or investigations are foreseen: Microscopies, Microhardness Permeation tests

Vacuum, Surfaces & Coatings Group Technology Department Conclusion C. Garion17 Glassy carbon is an interesting material for highly transparent vacuum components (chambers, windows), required in high energy physics domain. Glassy carbon could be an alternative to beryllium, especially for beam induced heat deposition cycles. Hiradmat can offer intense beam induced heat deposition and is an unique opportunity to validate the suitability of glassy carbon for vacuum windows in high energy physics. Thanks for your attention 14 March 2014 HiRadMat