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Glassy Carbon Tests at HiRadMat

Glassy Carbon Tests at HiRadMat. C. Garion CERN/TE/VSC. Outline: Introduction Context: Transparent material Figure of merit New material development Glassy carbon properties Test set-up Configuration Instrumentation Expected behaviour Result analysis. HiRadMat.

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Glassy Carbon Tests at HiRadMat

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  1. Glassy Carbon Tests at HiRadMat C. Garion CERN/TE/VSC • 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

  2. New material development for transparent UHV structures Material choice Transparency is related to: HiRadMat C. Garion

  3. New material development for transparent UHV structures– Figures of merit Several figures of merit, characterizing the material, can be used depending on the final application. • Mechanical Stability (buckling): • Temperature rise in steady state: • Temperature rise in transient regime: • Thermal fatigue: HiRadMat C. Garion

  4. New material development for transparent UHV structures Figure of merit for thin vacuum chambers HiRadMat C. Garion

  5. New material development for transparent vacuum chambers Figure of merit of different materials, normalized w.r.t. beryllium HiRadMat C. Garion

  6. New material development for transparent vacuum chambers Photon absorption of different materials, compared to beryllium HiRadMat C. Garion

  7. New material development for transparent vacuum chambers – Glassy carbon • 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. Glassy carbon tube HiRadMat C. Garion

  8. New material development for transparent vacuum chambers – Glassy carbon Mechanical properties: • Stiffness: • 4 points bending tests on plates equipped with strain gauges • Young modulus and Poisson’s ratio 4 points bending test on plates Elastic properties • Strength: • 4 points bending tests on bars (avoid chips during cutting) • Compression tests • Weibull’s distribution 4 points bending test on rods Survival probability for the bending test HiRadMat C. Garion

  9. New material development for transparent vacuum chambers – Glassy carbon Fracture toughness: • Notched bar under 4 points bending test: Notched bar • CT specimen: test in preparation CT specimen and crack propagation simulation  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 HiRadMat C. Garion

  10. New material development for transparent vacuum chambers – Glassy carbon CusilABA inteface layer Transition to metallic parts: • Soldering with intermediate ceramic part: • Compatible thermal expansion • Higher mechanical strength Ceramic Glassy carbon • 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 HiRadMat C. Garion

  11. New material development for transparent vacuum chambers – Glassy carbon Outgassing rate: • Unbaked material: • Throughput method • Grade K : high outgassing • Grade G : low outgassing Outgassing curve of unbaked glassy carbon • Baked material: • Gas accumulation method • Grade G : outgassing rate of 1.5E-13 mbar l s-1 cm-2 Outgassing of baked glassy carbon HiRadMat C. Garion

  12. Test Set-up - Configuration Aluminium tube under vacuum or inert gas SPS window Exit windows Glassy carbon disc, 50<<100 (tbc) HiRadMat C. Garion

  13. Test Set-up - Instrumentation • Instrumentation foreseen during tests at Hiradmat: • Fast camera • Strain gauges if relevant • Temperature sensors • LDV HiRadMat C. Garion

  14. Test Set-up – Expected behavior • Peak energy deposition: 1.8 J/mm3 • (one nominal LHC beam at beam dump entrance windows: 3.2E14 p+ @ 7 TeV) • s = 0.9 mm 3 mm HiRadMat C. Garion

  15. Result analysis • Following measurements or investigations are foreseen: • Microscopies, • Microhardness • Permeation tests Tests would be probably done (tbc) in the CERN metallurgy and vacuum laboratories. HiRadMat C. Garion

  16. Conclusion 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 HiRadMat C. Garion

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