Workshop on cryogenic & vacuum sectorisation of the SPL Vacuum Sectorisation

Workshop on cryogenic & vacuum sectorisation of the SPL

Vacuum Sectorisation

Paul Cruikshank, CERN

Technology Department (TE)Vacuum Surfaces & Coatings Group (VSC)

Topics

· Typical Vacuum Instrumentation

· Cold & RT beam vacuum

· Cryostat insulation vacuum

· LHC & LEP inputs· LHC Vacuum sectorisation · LEP cavity experience

· Sectorisation Variants for SPL· Advantages / Disadvantages

09-11-092Vacuum Sectorisation

Typical Beam Vac Config

09/11/09Vacuum Sectorisation 3

Typical Insulation Vac Config

·

09/11/09Vacuum Sectorisation 4

LHC; Arcs and LSS

Arcs: - 8 x 2.8 km = 22.4 km - cryomagnets in a continuous cryostat

LHC arcLHC LSS

LSS (Long Straight Sections): - up- and downstream of the experiments - 8 x 2 x 250 m = 4 km - room temp and standalone cryo-magnets

Cryogenic distribution line QRL

LHC Vacuum Overview

6

IP7IP8

LHC b

ARC IR8 LDS DS ARCIR8 RDSIR7 R

TI8

2456 m 170 m 269 m

beam 2

beam 1

> 300 beam subsectors

LHC Vacuum Overview

• A few numbers….

Characteristic Quantity for LHC machine & distribution line (QRL)

Insulation vacuum system length 22,4 km & 25 km

Welds ~ 250 000 (90 000 in-situ)

Weld length ~ 100 000 m

Elastomer joints ~ 18000

Elastomer joint length ~ 22 000 m

Multi-layer insulation ~ 9 000 000 m2 or 200 m2/m of cryostat

Vacuum subsectors 234

Vacuum subsector length 214 m (machine) & 428 m (QRL)

Vacuum subsector volume ~ 80 m3

Fixed turbo pumps 178

Nominal turbo pumping speed 0,25 l/s/m of cryostat

Fixed vacuum gauges 974

Mobile turbo pumping groups 36

Mobile primary pumping groups 36

LHC Vacuum Sectorisation

· LHC Sectorisation Working Group setup in 1995· Consider beam vacuum, insulation vacuum, cryogenic

layout· Increased flexibility ?· Reduce down-time ?· Analyse types of intervention

· Short – diode replacement, weld repair,instrument repair· Long – change of cryomagnet

· Additional equipment required?· Implementation Cost ?

· LHC Project Report #60 – September 1996· Quantifications, recommendations, (dis)advantages,

costs 09/11/09Vacuum sectorisation 8

LHC Sectorisation

· Long Straight sections· Low density of cold magnets (30+20+10+10m cryostats

in 250m) & lots of RT equipment – needed helium distribution line

· Beam vacuum sectorisation at each cold warm transition (CWT)

· Arc· Coherent vacuum & cryogenic subsectors to allow local

warm-up of 2.8 km continuous cryostat· Vacuum barriers and helium plugs every 214 metres -

compromise between staged installation, leak localisation, partial warm-up, additional heat inleaks, limit degraded vacuum

· No beam vacuum sectorisation in 2.8 km continuous cryostat

· QRL· Separation of QRL vacuum from magnet vacuum to

allow staged reception and leak localisation in long cryostats

09/11/09Vacuum sectorisation 9

Insulation vacuum sectorisation

LHC ARC: CRYOGENIC AND INSULATION VACUUM BASELINE DESIGN

Q7R Q9R Q11R Q13R Q15R Q17R Q19R Q21R Q23R Q25R Q27R Q29R Q31R Q33R Q33L Q31L Q29L Q27L Q25L Q23L Q21L Q19L Q17L Q15L Q13L Q11L Q9L Q7L

A B A B A B A B A B A C D A B A B A B A B A B A B A

Insulation Vacuum sectorization:

Magnet vacuum barriers Jumper vacuum barriers Cryogenic line vacuum barriers

Cold-mass sectorization:

Bus-bar plugs Safety relief valves Cooldown and fill valves

QRL vacuum jacket

Magnet vacuum vesselQ7R Q9R Q11R Q13R Q15R Q17R Q19R Q21R Q23R Q25R Q27R Q29R Q31R Q33R Q33L Q31L Q29L Q27L Q25L Q23L Q21L Q19L Q17L Q15L Q13L Q11L Q9L

Insulation Vacuum (3)

11

FBDC

KC'XYLE

V1V2

W

Z

LHCmagnetcryostat

QRLcryostat

Jumpers Vacuumbarriers

Baseline ‘short interventions’in insulation vacuum subsectors

• Scenario from LHC Project Report 60• Vacuum barriers every 214m

• n-2…. floating, cold, under vacuum• n-1 thermal buffer, RT, under vacuum• n intervention, RT, vented, W opened• n+1 thermal buffer, RT, under vacuum• n+2…. floating, cold, under vacuum

• With subsector length of 214m, it is necessary to warm-up 642m of the 2.8 km continuous cryostat

nn-1

Eg repairs on diode, busbar, line Y, helium leak….but no intervention on beam vac

n-2 n+1 n+2

Sectorisation of LEP RF CavitiesBeam Vacuum

• Commissioning and installation• During the installation and commissioning, the RF cavities

shall stay under vacuum to:• Limit the contamination by dusts

– Without any sectorisation, several venting will be required, increasing the risk of dust contamination.

• Preserve the RF commissioning on surface– Venting always implies repeating partly the RF commissioning

• During the pre-commissioning on the surface, absorber blocks have to be installed on the other side of the sector valves to absorb the accelerated electrons emitted by field emission. Once installed in the LEP tunnel, the sector valves were the absorbers.

• Modules were warmed individually to change tuners or couplers.

Sectorisation of LEP RF CavitiesBeam Vacuum

• RF processing is required to increase the accelerating field above 6 MV/m• Injection of helium (5.10-6 mbar, reading on the gauge) onto

the cold (4.5 K) RF cavity.

• Sequence is as follow:• Installation of a pumping group with an helium injection line (4 h)• Bake out (24 h)• Helium injection (3 h)…RF processing…• Helium pump down (10 h minimum) needs a partial warm-up to

release the condensed helium

Need that each module is sectorised to allow for an RF processing

SPL Sectorisation Variants


Continuous

SegmentedOption B

SegmentedOption A

Typical Insulation Vac Config

· Cost for vacuum system:

· Draft estimate from S. Calatroni

· Includes instrumentation, controls, cabling, in-situ leak test

· Insulation vacuum subsector ~ 90 kCHF

· Beam vacuum ‘cell’ ~ 90kCHF (cold) + 90kCHF (RT with valves)


SPL Sectorisation Variants

Volume types Max ‘Segmented’ Max ‘Continuous’

Insulation vacuum volumes - cryomodule

35((10+5)+6+(12+2))

3200m+90m+212 m

Beam vacuum volumes- cryomodule + intermodule

7135+35+1

73+3+1

Insulation vacuum volumes- helium distribution line

5 ?106m*5

0 or 1530m

Total vacuum volumes 111 10

09-11-09Vacuum sectorisation 17

Design aspects – vacuum

· Advantages· More modular design· Minimise cold equipment –

access, alignment, repairs, upgrades, unecessary outgassing, leaks, etc

· Modules are complete & tested before installation

· Disadvantages· More vacuum equipment

eg cold to warm transitions, intermodules

· More vacuum instrumentation

· Advantages· Compact longitudinal

layout – fewer CWT, fewer RF contacts

· Helium transfer line can be integrated – less vac systems

· Disadvantages· Beam vacuum sectors

long- cold sector valves don’t exist!

· Some sensitive equipment is imprisoned in cryostat - needs vacuum compatibility and validation

09-11-09Vacuum Sectorisation 18

Segmented Continuous

Installation aspects – vacuum

· Advantages· Minimise tunnel work and

problems - modules are complete and tested before installation

· Fewer problems treated on-line

· Staged acceptance tests· Decoupling of problems

· Disadvantages· Beam and insulation

vacuum systems are exposed to tunnel environment – dust contamination?

09-11-09Vacuum sectorisation 19


Repair aspects – vacuum

· Advantages· Reduced search zone· Decoupling of repair and

other activities · Limit zones of warm-up

and opening of vacuum system – cost & downtime

· Disadvantages· Difficult access at cold to

warm transitions – not std interconnect design

· Advantages· Less tasks for systematic

repairs on modules – venting, repumping..

· Disadvantages· Equipment will see more

thermal cycles – create leaks?



Commissioning aspects – vacuum

· Advantages· Precommissioning before

installation· Staged tests – smoothing

of resources, earlier identification of problems

· Decoupling of problems· Recommissioning of

‘weak’ module possible· Disadvantages

· More volumes to commission

· Disadvantages· Cavities need to be

recommissioned if vented· RF processing with helium

required for field above < 6 MV/m – complicated

· Movable blocks or valves to absorb field emission electrons?



Operational aspects – vacuum

· Advantages· Limit zone of degraded ins

vacuum (helium leak)· Easier diagnosis of

problems· Disadvantages

· More equipment (fixed pumping systems & valves)

· More interlocks· More risk of equipment

failure· More maintenance

· Advantages· Simpler controls· Redundancy in fixed

pumping systems· Disadvantages

· MCI would affect more equipment



SPL Vac Sectorisation – next steps

· Which sectorisation variants are not possible?

· Strong vacuum constraints need to be identified & investigated – eg can we expose cavity to tunnel air, etc.

· Constraints for other technologies to be confirmed

· For retained variants, advantages and disadvantages presently expressed qualitatively, now need to be quantified in time, manpower and expenditure.

· Are there other vacuum aspects to add?

· Continue to get feedback from other operational machines 09-11-09Vacuum Sectorisation 23

Last Slide

Thanks for your attention


ITER/CERN Collaboration - LHC Insulation Vacuum - Paul Cruikshank - 25 June 2009

Semi-standalone cryo-magnet- typical installation and leak test sequence -

HELIUM CIRCUIT

JUMPER

CRYO-MAGNET

CRYOGENIC DISTRIBUTION LINE (QRL)

CRYO-MAGNET

BEAM VACUUM TUBES

PUMP + DETECTOR

PUMP +

DETECTOR DETECTOR DETECTOR

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Workshop on cryogenic & vacuum sectorisation of the SPL Vacuum Sectorisation