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Materials for Phase II collimators

Materials for Phase II collimators. Rib Stiffener, why molybdenum. Stiffener material requirements: Minimise own thermal distortion Low CTE High thermal conductivity Minimise deflection by the force in the midpoint link High Young’s modulus. X-deflection simulation.

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Materials for Phase II collimators

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  1. Materials for Phase II collimators LHC Collimators Phase 2 - Visit to Plansee 28th August 2008

  2. Rib Stiffener, why molybdenum • Stiffener material requirements: • Minimise own thermal distortion • Low CTE • High thermal conductivity • Minimise deflection by the force in the midpoint link • High Young’s modulus X-deflection simulation Active part where most of heat is deposited tends to deflect due to thermal gradient Stiffener linked in a midpoint to limit deflection of the active part Link Shafts, fixed points LHC Collimators Phase 2 - Visit to Plansee 28th August 2008

  3. Stiffener, why molybdenum Al-C-fiber composites LHC Collimators Phase 2 - Visit to Plansee 28th August 2008

  4. Stiffener made of Mo, old monolithic version LHC Collimators Phase 2 - Visit to Plansee 28th August 2008

  5. Stiffeners made of Mo, assembled by bolts and pins • How are the stiffners Long plates 15 x 47 x 1100 mm³ Thinner extremities Circular holes and slots Tolerance ~0.1 mm Threaded holes for cooling clamps Spacers Positioning system Bolts and pins LHC Collimators Phase 2 - Visit to Plansee 28th August 2008

  6. EBW EBW Stiffener, raw material • Overall dimension of long plate (mm) • ≥15 x 47 x 1100 • Standard dimensions by Plansee • 12.7 x 500 x 600 • 20 x 500 x 600 • Possibility of having customized production • Ideas to make it out of standard dimension plate for prototypes (4÷8 plates), eventually for series (~250 plates) • EB butt weld • Connect overlapped plates, bolted or riveted • Also • Spacers • Positioning system • Bolts and pins LHC Collimators Phase 2 - Visit to Plansee 28th August 2008

  7. Stiffener, machining • Recommended machining parameters • Plansee as possible supplier of finished components • Tolerances achievable • Extremity holes • Positioning system elements • Do you see any other issue not mentioned? LHC Collimators Phase 2 - Visit to Plansee 28th August 2008

  8. Brazing Brazing Contact CuNi GlidCop C-C Cooling coil, interest of using molybdenum Phase 1, implemented solution: • Phase 2, increased energy deposition. • Cooling capacity has to be increased • 6 x tubes ID8 mm • reduce contact thermal resistance • Geometrical stability has to be maintained • use material with optimised k/CTE • Ideal solution: • Cooling coil back-casted in M-CD block LHC Collimators Phase 2 - Visit to Plansee 28th August 2008

  9. Cooling coil, interest of using molybdenum • Cooling coil material for Ideal solution requires • Metallurgical compatibility with metal of the block • Avoid dissolution of the coil in the liquid metal • Avoid inconvenient inter-metallic phases at the interface • CTE matching with M-CD • Avoid distortion, residual stresses or debonding at the interface when solidifying and cooling from infiltration temperature • Gaps at the interface leads to poor thermal conduction and virtual leaks • Feasibility of the coil • Cooling coil materials believed to be good candidates from the first two points of view • For Cu-CD: molybdenum,niobium, tantalum • For Al-CD: zirconium (preliminary test program is in progress in cooperation with L. Weber EPFL including also stainless steel) LHC Collimators Phase 2 - Visit to Plansee 28th August 2008

  10. Cu-CD Al-CD Cooling coil, interest of using molybdenum • Molybdenum coil in Cu-CD block • CTE • Phase diagram • Feasibility of the coil LHC Collimators Phase 2 - Visit to Plansee 28th August 2008

  11. Cooling coil, interest of using molybdenum Liquid Cu would dissolve Ti or Zr tube ! LHC Collimators Phase 2 - Visit to Plansee 28th August 2008

  12. Cooling coil, interest of using molybdenum Mo, Nb and Ta have limited solubility in liquid Cu and do not form inter-metallic phases LHC Collimators Phase 2 - Visit to Plansee 28th August 2008

  13. Cooling coil, interest of using molybdenum • Feasibility of long intricate coil is a question mark. • ID 8 mm x L 3800 mm • Bending radius as small as 18 mm • Tests and trials • Tensile test at RT on molybdenum tube OD10xID8 (our CA1491024) • Rp0.2 = 570 MPa Rm = 685 MPa • A ≥ 40% !!! but transversally very low ductility • Inner wall of the tube is oxidised • Bending tests to be done at CERN workshop • What are your recommendations? • Butt welding, your recommendations LHC Collimators Phase 2 - Visit to Plansee 28th August 2008

  14. Cooling coil, vacuum related constrains • Avoid virtual leaks (confined volumes with low aperture that make long time to evacuate) • Avoid any welding or brazing between water and beam vacuum !  use of continuous seamless tube • Other solutions if the last constrain can be relaxed: • Cooling circuit machined in a block, closed by brazing or welding • Brazed to the main block • Back-casted inside the main block • Any other? • Any experience in similar large surface brazing LHC Collimators Phase 2 - Visit to Plansee 28th August 2008

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