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Status of the Composite Vacuum Chambers. M. Gallilee, C. Garion, M. Malabaila, G. Schneider , S. Sgobba, M. Taborelli, R. Veness. Experimental Beam Pipes Materials Carbon Beam Pipe Production Design O ptions and Status Outlook. LHCb UX85/3. ATLAS.

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Status of the Composite Vacuum Chambers

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status of the composite vacuum chambers
Status of the Composite Vacuum Chambers

M. Gallilee, C. Garion, M. Malabaila,

G. Schneider, S. Sgobba, M. Taborelli, R. Veness

  • ExperimentalBeam Pipes
  • Materials
  • CarbonBeam Pipe Production
  • Design Options and Status
  • Outlook
G. Schneider TE/VSC

ALICE Central Beam Pipe Installation

beam pipe functionality list
Beam Pipe Functionality List


Leaktightness (<10-11mbar.l/s)

Bakeable (> 200 °C, ideally 300 °C)

Outgassing (<10-12mbar.l/(s.cm2)

Beam-surface aspects (photon, electron and ion desorptionyields)

Mechanically stable for all load conditions

Transparency to particles



Assure long-life





Courtesy R. Veness, V. Hedberg


And why not Beryllium?

  • Brittle
  • High cost (several 100 000 Chf/m)
  • Toxicvapours when machined
  • Longdeliveries
  • Limited number of suppliers

Why do wewantcarbonmaterial?

… but carbon fibre composite isalso attractive



carbon fibre tube 1
Carbon Fibre Tube (1)

Carbon fibres are about 0.005 to 0.01 mm thick

Severalthousand fibres twistedtogethermake a yarn

Make a fabric out of the yarn

Wind the fabric or yarnaround a mandrol (tube) in any angle between 0° and 90°

carbon fibre tube 2
Carbon Fibre Tube (2)

Add filler material


Epoxy, tar, …

Cure in an autoclave at 150 °C to 230 °C

Cure at 2000 °C

Carbon-Epoxy tube

High Youngsmodulus (200 GPa)

Max. bakeouttemperature 230 °C

Outgassing not vacuum compatible

Carbon-Carbon tube

Good Young modulus (100 GPa)

Max. bakeouttemperature no issue

Outgassing vacuum compatible


Composite Tube developmentsat CERN in the 80’s

Carbon – Epoxi tube wasinstalled in LEP experiment

Total Thickness 1.24 mm

Diameter 106 mm

Internal aluminium liner of 0.1 mm

 Enventuallyfailed, since the aluminium delaminatedfrom the carbon structure

vacuum barrier inside
Vacuum Barrier Inside

Glue aluminium liner to carbon composite tube

Lookingintocompaniesinterested in the supply

Lookinginto options to increase the resintemperaturestability. Current options are epoxy, polyimide, cyanite-ester

Quotationexists (QinetiQ) for vapourdeposition on carbon composite samples to test leaktightness


Copper layer on carbon by electroplating

Test made: Not 100 % surface coverage due to « rough » surface of the windings. Corrosion due to plating bath coming out from the matrixafter the coating

vacuum barrier outside
Vacuum Barrier Outside

Carbon Tube with Vacuum BarrierOutside

Advantage: Air pressure will push the liner on the carbon

Disadvantage: Carbonwillbeseen by the beam

Carbon Tube


vacuum barrier outside 1
Vacuum Barrier Outside (1)


Outgassing tests were made on a SGL CarbonSigrabond Tube of type 2001 G diameter 104/100 mm inside a 300 mm long Titanium Grade 2 tube 0.3 mm thickwithTitanium 5 Conflatflanges.

Result: The outgassing rate is about 1x10E-12mbar.l/( 2)

Test temperature: 250 °C

No leaks of the titaniumconflat to stainlesssteelconflatfound up to 250 °C

vacuum barrier outside 2
Vacuum Barrier Outside (2)

Spectrum of carbon-carbonbeam pipe in Ti-vacuum barrierafterbakeoutat 200 °C

beam impedance
Beam Impedance

Benoit Salvant BE/ABP isworking on the subject.

5 micron of aluminium coatinginside the carbon tube seems to besufficient

vacuum barrier material
Vacuum Barrier Material

 We go for aluminium in order assure maximum transparency

exotic solutions
“Exotic Solutions”

Carbon fibre aluminium composite

Exists, but only in smalldimesions. Trying to findmanufacturers

Honeycomb structure instead of carbon

In principle the technologyexists, but weneedverythin aluminium foil on eitherside of the honeycomb and we have hightemperatures

next development steps
Next development steps

Check how the Carbon-CarbonYoungsmoduluscanbeincreased

Look for hightemperatureresins

NEG coating on carbonbeam pipe

Increaselength of test beam pipes to 2 m

Study how beam pipe lengthcanbeincreased to 8 m

Procure if possible Carbon-Aluminium tube

Studyhoneycomb structure

Support: 12 Studentsfrom Oxford Universitygiven 3rd yearproject to study alternatives to beryllium (M. Gallilee)

composite chambers 5 year roadmap
Composite Chambers 5 Year Roadmap

0.3 m Alu outer vacuum barrier/Carbon-carbon with NEG

0.3 m Carbon-epoxy*/Alu liner (glued or deposited)

2m test chamber #1

Test chamber in SPS

2m test chamber #2

0.3 m Carbon-Al composite

* Or otherhightemperaturepolymerlikepolyimide, cyanate-ester…

Mid 2012