presented by Paul C ruikshank

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presented by Paul Cruikshank

with input and contributions from: V. Baglin, N. Provot, W. Maan TE/VSC, and the team working on the DS collimator project

Review of the cryogenic by-pass for the LHC DS Collimators

Vacuum Design May 26, 2011

Recall: Rules of the game... No halogenated fluxes to be used anywhere

Vacuum brazing only No ‘helium-to-beam vacuum’ welds (or brazes)

Partial penetration welds only No demountable vacuum tight joints in cryogenic system No ‘metal/ceramic’ vacuum tight joints in cryogenic system Vessel walls with material lamination (inclusions) parallel to wall

surface, otherwise forged material. Minimise the number of thin-wall components

Favour flexible pipe loops to braided hoses All components and subassemblies to be leak tested before

installation Combined pressure & leak test of finished assemblies tooling Thermal cycle of cryo assembles is strongly recommended

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Design Principles General

To minimise the work and reduce risks use validated designs – beam screens, PIMs, cold-to-warm transitions, cryostat construction, vacuum instrumentation.

Beam vacuum Separation of cold and warm sectors with sector valves Room temperature system is bakeable and equipped with

permanent bakeout heaters (integration & radiation issue). Removal of collimator without warm-up of arc RF ball interface to validate PIM status in arcs 2-3 and 3-4 Each cold volume has adequate pressure relief

Insulation vacuum Integrate the collimator cryostat into the existing vacuum subsector Each subsector has adequate pressure relief

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Beam vacuum sectorisation eg IR3L

New beam vacuum sectors are created – cold & room temp 16 additional sector valves in IR3L & R

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Cold vacuum sector Q7L to Q7R RT vacuum sector

Before

After

Beam vacuum sectors

New RT vacuum sectors are instrumented as LSS zones New cold vacuum sectors will have at least one rupture disc as

part of the arc beam vacuum consolidation in LS1

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Beam vacuum – sector valve constraint

Actuator of the sector valve must be removed to fully open W sleeve on the right Sector valve remains locked closed by design The arc is always at RT for the intervention The leak tightness can be monitored In case of problem, the collimator could be re-

baked in the shadow of the arc cool down Actuator demounting has been validated

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RF Ball implementation

RF ball test in LHC baseline to verify PIM integrity after warm-up Existing interfaces at arc extremities Ball cannot travel thro’ DS collimators (too large cross-section,

vacuum integrity, sector valves closed) New interface at QTC – DN35 flange on ‘cold side’ – also used

for vacuum gauges. PIMs will all be consolidated in Q11 to Q7 zone - only need to

perform RF ball on arc side

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Vacuum system assembly

Vacuum component preparation Shopping list is complete Validation of detail drgs by end June – then manufacturing of first beam screens in main

workshop - to be delivered 31st October 2011.

QTC and Connection Cryostat preparation Beam screen, cold-to-warm transition and PIM integration very similar to arc SSS and

diploes Beam screen integration work will be combined with other SSS and dipole preparation

at a single site – SMI2? fragile components, single team ,single assembly zone, centralisation of tooling

Collimator & other RT components ‘Lego’ components will be prepared as for LHC in building 113 and 252 Some pre-mounting of RT components on the QTC (eg sector valves) is under

discussion

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Insulation vacuum issues Adequate cross-section for pumping through by-pass cryostat 0.18

m2 ~ C 3000 l/s MCI pressure relief configuration to confirm for subsector

Existing equi-spaced pumping ports for additional mobile pumps if

required at Q11, Q9 and Q7 Radiation exposure of fixed pumping group at Q8

exposure of equipment during operation & personnel during routine maintenance

move to Q9 - to discuss Standard in-tunnel leak testing works

Machine interconnects Jumper inetrconnects New cryo-extension (Q9, Q7 and DFBA)

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Operational considerations Risks for operation start-up

Significant modification to LHC vacuum systems at IR3 A lot of new vacuum hardware to be installed and tested New cabling and revised controls software Time must be reserved for system tests

Risks for operation More hardware in the tunnel – reliability & maintenance Collimators are very near to cold arcs - particle showers from the collimators

may produce vacuum instabilities (eg heat loads to beam screens) resulting in sector valve closures

The beam vacuum design been made to mitigate against instabilities Similar configurations already exist eg near Q4 Clone of the existing LHC vacuum design Conditioning of the collimators prior to installation & in-situ bakeout Adequate pumping speed from ion pumps & NEG Beam screens in QTC to provide vacuum stability and adequate pumping

No major operation concerns

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Thank you for your attention!

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