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Phase II Collimators at CERN: design status and proposals

Phase II Collimators at CERN: design status and proposals. EuCARD/ColMat kick-off meeting 17 th June, 2009. Alessandro Bertarelli. Who at CERN. Mechanical Engineering: Alessandro Bertarelli, Alessandro Dallocchio, Ricardo de Morais Amaral

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Phase II Collimators at CERN: design status and proposals

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  1. Phase II Collimators at CERN: design status and proposals EuCARD/ColMat kick-off meeting 17th June, 2009 Alessandro Bertarelli

  2. Who at CERN Mechanical Engineering: Alessandro Bertarelli, Alessandro Dallocchio, Ricardo de Morais Amaral Material Science: Gonzalo Arnau Izquierdo, Romain Blanchon, PhD student Mechanical Design: Roger Perret, Arnaud Bouzoud, Bruno Feral, Marc Timmins Manufacturing: G. Favre, L. Ferreira, A. Cherif Plus many more from EN, TE and BE departments

  3. Limits of Phase I Collimators • Resistive Impedance According to RF simulations, Phase I Collimator Impedance would limit LHC beam intensity to ~40% of its nominal value! • Cleaning efficiencyCleaning efficiency (i.e. ratio escaping protons / impacting protons) should be better than 99.998% to limit risks of quench in Super Conducting magnets. Simulations predict a beam intensity limited to ~40% of Inom for perfect collimators. • Radiation HardnessOngoing tests anticipate risks of degradation of Carbon/Carbon jaws (reduction of thermal and electrical conductivity, swelling, dust …) • Set-up and calibration timeStandard methods, based on measurement of beam loss generated by jaw adjustment, lengthy, requiring specific low intensity fills

  4. Phase II goals • Gain factor ≥10 in cleaning efficiency. • Gain factor ≥10 in impedance. • Gain factor ≥10 in set-up time (and accuracy?). • Radiation hardness and easy handling. • Improved geometrical stability (in operating conditions) 20 mm • Sufficient robustness (like Phase I?). • RWA May 2008

  5. Phase II Design Features • Jaw design • Modular design (a common baseline for the jaw assembly allows the use of alternative materials for the jaw). • Back-stiffener concept to allow maximum geometrical stability (improves collimator efficiency). • Adjustable system to allow jaw flatness control and compensate gravity sag (2 versions being studied … ) • Optimized internal cooling circuit to absorb higher heat-loads. • Integrated BPMs to minimize set-up time. • Jaw materials (goals) • Tailored electrical conductivity to improve RF stability. • High thermo-mechanical stability and robustness. • Higher density (high-Z) to improve collimation efficiency. • Strong resistance to particle radiation.

  6. Phase II Design options …depending on RF and cleaning efficiency specifications…

  7. Alternative Materials Metal jaw (high electrical conductivity) vs. Ceramic jaw (non-conductive) on metal conductive support...

  8. Phase II Design baseline (v1) Modular concept to fit in alternative jaw materials ... EQUIPPED JAW BRAZED COOLER FINE ADJUSTMENT SYSTEM BACK-STIFFENER

  9. Equipped Jaw (v1) 1st version of equipped jaw (1 adjustable support) … SiC absorber shown … Ceramic tiles SiC brazed on metal (conductive) support …Cu-CD is favorite candidate Machined cooling circuit with brazed cover. Fine adjustment system

  10. Design Baseline (v2) RF contacts ensure electrical conductivity between jaw pieces Alternative design of equipped jaw based on 2 intermediate adjustable supports … Fine adjustment system Mo Back - Stiffener Cut jaw: each piece is independently supported on the back stiffener. Enhanced geometrical stability

  11. Design Baseline (v2) 3-pieces jaw independently cooled by three separate brazed coolers Jaw Jaw - Stiffener Machine cooling circuit with brazed covers Back - Stiffener

  12. Cooler prototype Using high Z-material leads to higher energy deposition (up to a factor 5 increase w.r.t. Phase I). Higher cooling capacity is essential to ensure geometrical stability… Two prototypes including machined circuit, brazed cover and jaw mock-up have been produced and successfully tested…

  13. Cooler prototype The goal is to define a complete and standardized procedure according to UHV specs. in order to qualify the design. Jaw mock-up Test successfully performed: • He leak detection • Ultrasound cartography of the brazing surfaces • Pressure test (100 bar over 1h) • Final He leak detection. Machined circuit Brazed cover

  14. BPM functional prototype Graphite inserts BPM cables OFE-Cu jaw support OBJECTIVES: • Lab. tests to start April/ May 2009 • Beam tests in SPS during 2010 run (installation dates to be determined …) Mechanical design of simplified jaws featuring BPMs… BPMs BPM buttons Motivation: BPMs integration strongly influences the design of the whole system. A rapid testing in the SPS of the BPM embedded system is mandatory to validate the concept.

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