Phase II Collimators: design status, options and future outlook

1. Phase II Collimators: design status, options and future outlook LHC Collimation Phase II 9th Specification Meeting 7th November, 2008 Alessandro Bertarelli Alessandro Dallocchio

2. Overall time plan …excerpts from last LHC MAC (R. Assmann talk)… Scheduling (out of date?): • Define general directions until July 08. • Prepare conceptual design until October 08. • Discuss conceptual design and organize project details in November 08. • Testing of hardware in 2009/10 (lab and beam tests). • Time plan will be (is already?) affected by start of LHC beam operation (highest priority to make phase 1 collimation system work). • Important milestone: Review of conceptual design with parallel development paths in late autumn 2008.

3. Functional Specification 3 Phase II ultimate goals for TCSM baseline: • 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 to ensure LHC operability in case of accident.

4. Functional Specification Design Guidelines as we see them … • Modular concept to fit in alternative jaw materials (All-metal, Metal-diamond, Ceramics-metal, Thin foil etc.) and concepts (alternative cooling systems) • Increase geometrical stability and precision (e.g. jaw flatness). • Increase cooling capacity (doubling water flow-rate). • Capitalize Phase I experience to improve existing design (e.g. new moving tables, integrated electrical clutch) • Collaboration with external partners to identify, develop and test novel advanced materials (EPFL, Plansee, Politecnico di Torino, Kurchatov, BNL) • Possibility to embed in jaw design Beam diagnostic devices (BPMs, BLM(?) …)

5. Baseline of the design Fine adjustment System Jaw+cooling system Rigid Support (back-stiffener) Preliminary design is based on the concept of a back stiffener remaining at uniform temperature and ensuring geometrical stability of the jaw beam. Metal support (cooler) Jaw (monolithic case shown) Back stiffener

6. Baseline of the design Main components of Phase II jaw assembly: • Back-stiffener • Fine adjustment system • Equipped Jaw • Collimation Jaw • Jaw Cooling system • Beam diagnostics devices • RF system

7. Molybdenum Back-stiffener The design is already at an advanced stage, Mo seems to be the best candidate. PLANSEE confirmed the feasibility of this component (10-12 weeks to produce a prototype). Stiffener material requirements: Minimise thermal bending Low CTE High thermal conductivity Minimise deflection provoked by the force in the adjustable system High Young’s modulus MOLYBDENUM Fine adjustable systemsupport fastened to plates Stiffener plates (~1.1 m long; up to 20 mm thick) Stiffener ribs fastened to plates

8. Fine adjustment system …feasibility of Mo screws confirmed by PLANSEE… Cooling pipes on the stiffener plates (geometrical stability) Fine adjustment system (overall deflection controlled)

9. Jaw and cooler: Design options …depending on RF and cleaning efficiency specifications…

10. Collimation jaw Possible design options: • Monolithic metallic jaw (Glidcop) – Studied. • Monolithic Cu-diamond + Cu coating – Being studied • Preliminary design submitted to Plansee. Collaboration details to be discussed • Monolithic Al-diamond + Al coating – Being studied • Collaboration with EPFL already launched: Al-CD jaw + Al coating + Al-CD cooler with Zr or Inox pipes mock-up possibly available within few weeks. • Ceramic tiles on metal support – Being studied • SiC has been chosen as potential candidate following preliminary RF spec. SiC tiles samples purchased. Test ongoing to verify brazability of the ceramic tiles on the metal support. • Thin metal foil on low conducting support – To be studied • Preliminary RF studies show that no major difference exists between monolithic metal jaw and thin metal foil bonded on low conducting support. Possible advantages in terms of robustness. Diamond coating to be studied?

11. Collimation jaw Ceramic absorber with metallic (conductor) support… Metallic support Ceramic tiles

12. Jaw Cooler and pipes Increased energy deposition (high / medium density jaw materials) requires much higher cooling capacity with respect to Phase I (factor ~5) Design alternatives: • Machined circuit with brazed covers (Glidcop or Cu-Diamond) – studied. • High cooling capacity, relatively easy production. • Not in line with UHV recommendations → …(Remark: Plansee developed and qualified a very similar solution for ITER project in a similar environment) • Continuous bent pipes back-cast in metal diamond – being studied • Plansee available for co-development using Ta or Nb pipes in Cu-CD (Preliminary design submitted to Plansee. Collaboration details to be discussed) • EPFL also working on this option using Zr or Inox pipes in Al-CD (mock-up under manufacturing) • Machined circuit sealed during casting – To be studied • Continuous bent pipes brazed to jaw cooler – Derived from Phase I solution

13. Jaw Cooler and pipes Cooling circuit machined in metal support with brazed covers Cooling pipes back-cast in metal support

14. Cooler prototype A prototype of machined circuit with brazed covers is under manufacturing: • Jaw mock-up (Glidcop) • Machined circuit (OFE Cu or 316LN) • Cover (316LN) • Inlet and outlet water pipes (316LN)

15. Cooler prototype Two prototypes being realized with different materials for the machined circuit. The goal is to produce and qualify a brazed joint circuit meeting UHV requirements. Objectives: • Verify the brazability of the components and optimize the brazing process. • Test different materials • Verify the quality of the brazing. • Verify geometrical stability of the components after brazing. • Define a procedure for testing the tightness of the circuit. • Test with high pressure in order to establish the maximum allowed pressure. • Define a procedure for systematic ND control (e.g. ultrasound) of all brazed joints. • Put the prototype in UHV tank and verify potential leaks before and after high pressure tests. • Define a complete and standardized procedure according to AT-VAC specs. in order to qualify the design.

16. BPM integration Integration of BPMs into the jaw assembly gives a clear advantage for set-up time BPM pick-ups BPM cables and electrical connections

17. BPM functional mock-up PROPOSAL: Install a functional prototype in the SPS ring (LSS5 PROTO1 emplacement) featuring a simplified jaw with integrated BPM. Develop a prototype for laboratory tests. Phase I PROTO3 Simplified jaw: Embedded BPMs OFE Cu + Graphite inserts

18. BPM functional mock-up Motivation: BPMs integration strongly influences the design of the whole system. A rapid validation of the BPM embedded concept is mandatory to progress on the good path. Objectives: • Verify the effectiveness of the BPM embedded system. • Quality of the signal • Side effects of the particles on the BPM system • Validate present design solution • Number and position of BPMs. • Dimensions of BPM buttons. • Perform tests in SPS during 2009 run (installation before end of next shut-down)

19. BPM functional mock-up Requirements: Proto 3 collimator for SPS tests. Additional collimator tank (opened) for lab tests Estimated material costs: 25000CHF per prototype. Support from AT-VAC for bake-out, AB-ABP and AB-ATB for installation. Collaboration with AB-BI for design, procurement and electronics.

20. RF contacts RF stability provided by ferrite blocks and metallic rails (no sliding contacts) Ferrite blocks ensure beam stability without sliding contact Ferrite blocks placed all along the jaw Metallic rail

21. Collimation Tables Increased stiffness Linear ball bearings + shaft guiding

22. Future Outlook Thermo-mechanical calculations ongoing in order to assess the performances of different design solutions. RF studies have not yet allowed the choice between high/low electrical conductivity materials  keep all material options open (metal, ceramic, thin foil). Manufacture and test prototypes and mock-ups in order to validate some key features (BPMs and cooling systems). Increase reliability of actuation system by new moving table design. Continue/strengthen collaboration with EPFL and Plansee.