Status of vacuum & interconnections of the CLIC

main linac modulesC. Garion TE/VSC

TBMWG, 9th November 2009

Outline

• Vacuum system for the modules vacuum chambers pumping system

• Interconnections drive beam main beam

• Summary & conclusions

Vacuum system of the moduleVacuum chambers

PETSAccelerating structures

Vacuum chambers are mainly PETS or AS

Spec: EDMS 992778, 954081

PMB ~ 10nTorr

RiMBP 3 mm (now baseline is 4 mm)

material: copper (or Cu coated)

Spec: EDMS 992790

RiDBP 11.5 mm

Vacuum chambers of the drive beam

Drift tube Quadrupole

For both cases, precision tubes in stainless steel can be used (23 *1 in 316L). The length is ~270mm or ~580 mm for long drift tubes. Vacuum chamber will be copper coated.

Quadrupole chambers can be centered with 2 “soft” rings (PEHMW).

Pipe

Pole

Ring

Tolerances on quad poles are needed to fix the design.

Vacuum chambers of the main beam quad

Design:

Stainless steel vacuum chamber, squeezed in the magnet

NEG strips sited in 2 antechambers

Copper coated (thickness to be defined)

NEG strip

8-10 mm

50 mm

Stainless steel

Ceramic support

Spacer

Tooling has been done for Quad radius of 4 mm to be redone for final aperture ( 10 mm)

Final cross section is needed to check integration of the vacuum chamber in the magnet

Supporting or insulation of NEG strips have to be improved

Spacer have to be improved

Probably not needed for module prototypes

Pumping system

Vacuum equipment (version sealed disk): manifolds around the accelerating structures linked to a common tube Tanks around the PETS linked to a common tube MB and DB vacuum coupled via the common manifold and the waveguides

pumping system: mobile turbomolecular station + holding ion and cartridge pumps

Ion pump

2 NEG cartridges pumps

Tank4 linked Manifolds/AS

Pumping system performances: static vacuum

P100h~8.7E-9 mbar (for a link tank/manifold with a radius of 30mm)

Assumptions:

• q~10-10mbar.l/s/cm2 (after 100 hours of pumping)

•Pumping speed for 1 accelerating structure= 300 l/s

• 4 manifolds 30 mm*30 mm

8.2E-09

8.3E-09

8.4E-09

8.5E-09

8.6E-09

8.7E-09

8.8E-09

8.9E-09

9.0E-09

9.1E-09

0 5 10 15 20 25

Longitudinal abscissa [cm]

Pre

ssu

re [

mb

ar]

At that time, a minimum radius of 30 mm has to be reserved for the tank/manifold link

Model based on thermal/vacuum analogy

140m

m

0.00E+00

2.00E-09

4.00E-09

6.00E-09

8.00E-09

1.00E-08

1.20E-08

25 30 35 40

Radius of tank/manifold link

Ave

rag

e p

ress

ure

[m

bar

]

H2

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00

Time [s]

Pre

ssu

re [

mb

ar]

Thermal 1 Manifold Thermal 4 Manifolds MC

Assumptions: – 1012 H2 molecules released during a breakdown – Gas is at room temperature (conservative)

Dynamic vacuum in the accelerating structures

MC model

Thermal model

Monte Carlo model and thermal study are in good agreement

Dynamic vacuum in the accelerating structures

Not a “big” difference between 1 or 4 manifolds

Depending on the species, the local pressure doesn’t exceed the range 10-8-10-7 mbar after 20 ms.

Only 1 manifold could be needed (to be confirmed)

CO

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00

Time [s]

Pre

ss

ure

[m

ba

r]

4 Manifolds 1 manifold

1 Manifold

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00

Time [s]

Pre

ss

ure

[m

ba

r]

CO H2

Other issues: other dynamic effects (RF, beams) to be considered

Pumping system

Still to be done:

-Link between the loads and the tank

-Compensation and connections between the tank and the main and drive beams (for the prototypes, maybe a bellows with 2 standard flanges)

Interconnections - Drive beam

PETS/BPMQUAD/PETS QUAD/PETS IC

(or QUAD/drift tube IC)

Free space: 20mmFree space: 30mm

Drive beam – QUAD/PETS intramodule interconnections

Vacuum enclosure delimited by a bellows and knife flanges

Electrical continuity done by a copper based flexible element

Installation position

Working position

Flange integrated at the PETS extremity (to have same “free” plane as MB for tunnel installation). Is it acceptable?

Drive beam – QUAD/PETS intramodule interconnections

Stainless steel flange brazed on the PETS

Spring washers

Stainless steel bellows:

ID:45 mm, OD: 58 mm, 5 convolutions, 0.1mm thick, Pitch: 4 mm

Flexible “tube”

Copper rings

Gasket/flange assembly (with screws)

Schematic artistic view of the flexible element

Thin foil (0.1mm) in copper based material

Is there any requirement for the electrical conductivity?

Drive beam interconnections

Design of drive beam interconnections exists.

To be confirmed:

Space available in the magnet extremities (outer diameter of the bellows)

Number of cycles needed for the design of the flexible element

To be done:

Detailed design of the flexible element (geometry and material)

PETS/drift tube connection: permanent or dismountable connection?

Optimisation of the flange and knife (not mandatory neither for the module prototypes nor for the CDR)

•QUAD/PETS intermodule interconnections: same interconnection as QUAD/PETS Intramodule but with longer flexible element and bellows (6 convolutions)•PETS/BPM intermodule interconnections: same interconnection as QUAD/PETS intermodule but with different flange on PETS

QUAD/ASAS/BPM IC

(or AS/AS IC)AS/AS

Free space: 30mm 20 mm15mm

Interconnections - Main beam

Main beam – QUAD/AS intra & intermodule interconnections

intramoduleintermodule

Damping material What is the maximum transverse

displacement expected (1mm)?

Copper tube

Stainless steel bellows:

ID:25 mm, OD: 36.5 mm, 4 or 9 convolutions, 0.1mm thick, Pitch: 2.7 mm

Updated from Riccardo’s inputs

Main beam – AS/AS intermodule interconnections

Gap 9 mmCopper tube

Damping material

Stainless steel bellows:

ID:146 mm, OD: 166 mm, 4 convolutions, 0.1mm thick, Pitch: 4 mm

Screws?

Main beam – AS/AS intramodule interconnections

Copper “flexible” elementRequirement for the electrical conductivity?

Case 1: only 1 longitudinal fixed point for all AS on the module

AS AS AS

Precision of the longitudinal assembly?

Main beam – AS/AS intramodule interconnections

Copper “flexible” elementRequirement for the electrical conductivity?

Case 2: 1 longitudinal fixed point on each AS on the module

AS AS ASA bellows is needed

Main beam interconnections

Design exists for main beam interconnections.

To be confirmed:

Space available in the magnet extremities (outer diameter of the bellows)

Maximum misalignment to be compensated.

Fixed point for the accelerating structures

To be done:

Interconnection AS/BPM: critical because tight space and transition with the quad vacuum chamber.

Optimisation of the flange and knife (not mandatory neither for the module prototypes nor for the CDR)

• Optimization has been done

• Prototypes have been manufactured and are being tested (to be sent to SLAC)

Interconnections – inter beam waveguide flanges

Conclusion

Concepts for the vacuum system and the interconnections exist.

•Distributed pumping for main beam quad

•Common tank equipped with pumps linked to AS, PETS and drift tubes

•Sealed technology of the vacuum interconnections (with electrical continuity for the drive beam and a gap for the main beam)

Few questions are pending. Mainly related to:

•Interfaces with surrounding elements: Quad, AS, PETS, BPM, …

•Specifications for the interconnections: stroke and misalignment, fatigue life, electrical conductivity,

Main parameters for most of the components have been determined.

Detailed design can start after the green light.