status of vacuum & interconnections of the clic main linac modules c. garion te/vsc tbmwg, 9 th...
TRANSCRIPT
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.