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Alignment and assembling of the cryomodule. Yun He, James Sears, Matthias Liepe MLC external review October 03, 2012. Outline. Requirements and challenges Differential thermal contractions Material properties Axial differential thermal contractions among components at cold - PowerPoint PPT Presentation
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Alignment and assembling of the cryomodule
Yun He, James Sears, Matthias Liepe
MLC external reviewOctober 03, 2012
10/3/2012 Yun HE, MLC External Review 2
Outline
Requirements and challenges
Differential thermal contractions• Material properties• Axial differential thermal contractions among components at cold• Beamline vertical thermal contraction at cold
Dealing with differential thermal contractions • Position change between vacuum vessel and coldmass• Position change between HGRP and beamline• Position change between 40K shield and coldmass
Assembling steps
10/3/2012 Yun HE, MLC External Review 3
Requirements and challenges
Requirements
Allowable transverse offset (x,y): 2mm for cavities, 1.6 mm for quads Allowable pitch: 1.5 mrad (1.2 mm over the length of cavity)
Alignment is performed at room temperature
Tolerances maintained throughout thermal cycling, vacuum pumping and transport
Challenges
Different material coefficients of thermal expansion among interfacing components
10/3/2012 Yun HE, MLC External Review 4
Differential thermal contractions
•Temperature dependent material properties •Axial differential thermal contractions among components at cold•Beamline vertical thermal contraction at cold
Table from Norihito. Ohuchi’s talk, SRF2009
Table from Carlo Pagani’s paper, SRF2005
Material properties -- coefficient of thermal expansion
Material Temp. ∆L/L
G10 warp 300K- 2K -0.256%
SS 316 300K-2K -0.319%
Al 300K-40K -0.350%
Ti 300K-2K -0.172%
Nb-Ti 300K-2K -0.169%
Data from NISTUsed material data from NIST for calculations
Most of these values are higher than TTF used
10/3/2012 Yun HE, MLC External Review 6
Axial differential thermal contractions among components at cold
Fixed point
9.8 m, vacuum vessel at room temperature
9.5 mm -- HGRP
19 mm – thermal shield
8 mm – beamline
Axial displacement due to thermal contractions of materials at cold Components Material Temperature ∆L/L ∆L
HGRP Ti 300K-2K 0.172% 17 mm
Thermal shield Al 1100 300K-40K 0.350% 34.5 mm
Beamline (cavity) Nb/SS 300K-2K 0.146% 14.5 mm
7.5 mm -- HGRP
15.5 mm – thermal shield
6.5 mm – beamline
Sliding postSliding post
1 mm thermal contraction – cavity LHe vessel
0.8 m
10/3/2012 Yun HE, MLC External Review 7
Vertical beamline displacement at cold
500
mm
140
mm
Components Material Temperature ∆L/L ∆L
HGRP/LHe vessel
Ti 300K-2K 0.172%
0.9 mm
Post G10 300K-2K 0.256%
<0.3 mm
40K
5K
Moved up by ~1.2 mm
10/3/2012 Yun HE, MLC External Review 8
Dealing with differential thermal contractions •Position change between vacuum vessel and coldmass•Position change between HGRP and beamline•Position change between 40K shield and coldmass
Longitudinal: middle post is fixed, while the side posts are slid able
Vertical: Bellows section allows displacements of beamline at cold• Beamline port on end flange of warm-cold transition will be higher by 1.2 mm, so the bellows will be bent at room temperature
Coupler design allows a transverse offset up to10 mm• Couplers will be offset at room temperature thus will be straight at cold
9
• Brass bushing allows side post to slide on vacuum vessel top flange
• Replace it with roller bearings?
Dealing with position change between vacuum vessel and coldmass
10/3/2012 Yun HE, MLC External Review
10/3/2012 Yun HE, MLC External Review 10
Cavity flexible support • Allows 1 mm displacement
A bellows section in chimney of cavity
Key alignment of component supports• Allows beamline components to slide longitudinally relative to HGRP
Bellows in HOM absorbers• HOM loads are made of stainless steal but the bellows in the HOM loads will take the difference
between the length changes of the cavities and HOM loads and the HGRP
Alignment results from Injector Cryomodule WPM measurements• Cavity string was aligned to 0.2 mm after cool-down
Dealing with position change between HGRP and beamline
11
Fixed postSliding postSliding post
Left/right posts can move relative to shield in axial direction during cool-down
At room temperature, side post is offset to vac vessel port centerConcentric to shield opening
At cold, side post is moved due to HGRP contraction, became concentric to vac vessel port centerSlightly offset to shield opening center
10/3/2012 Yun HE, MLC External Review
Dealing with position change between shield and cold mass (posts)
10/3/2012 Yun HE, MLC External Review 12
Assembling steps
10/3/2012 Yun HE, MLC External Review 13
Assembling steps -- assemble beamline , weld 2K-2 phase line
Assemble beamline in the clean room on rail support; Leak check and keep beamline in UHV
• Level components in horizontal direction (Roll) with sine-plate within 0.0005”/10”;• No need to align them in other directions as bellows in HOM absorbers allow for adjustment once the
beamline string is mounted to precision machined HGRP supports
Weld 2K-2 phase pipe to chimneys of cavity/magnets LHe vessels;
10/3/2012 Yun HE, MLC External Review 14
Assembling steps -- assemble beamline , mount to HGRP/posts
Mount beamline string onto HGRP which is supported by three posts on assembly frame;
Install tuners
Connect supports
Weld chimney between HGRP and 2K-2 phase pipe
10/3/2012 Yun HE, MLC External Review 15
Assembling steps – insert cooling lines, instrumentation wires,40K shield
Install 2K, 5K cooling pipes; Install 40K shield upper sheets and 40K cooling pipes; Connect jumpers to 5K, 40K intercepts; Instrumentation wires Install 40K shield lower sheets; Magnetic shields; MLI
10/3/2012 Yun HE, MLC External Review 16
Assembling steps – insert cold mass into vacuum vessel
Rail cold mass into vacuum vessel; Mount alignment brackets to support post; Jack up brackets to relieve the cold mass weight from rails; Align post position with respect to the vacuum vessel fiducial points
Rails for cold mass insertion
Alignment bracket
Vacuum vessel reference arm, with precision machined conical centering surface for a TH-sphere or reflector
Position of posts can be adjusted via rods/screws
1710/3/2012 Yun HE, MLC External Review
Assembling steps – align cold mass to vacuum vessel references
• Adjust positions of posts relative to vacuum vessel reference arms;• Lock the position of middle post and the position of side posts in horizontal direction;• Install cryogenic valves; • connections of valves to pipes
Support post
Support bracket
Reference surfaces for TH spheres
10/3/2012 Yun HE, MLC External Review 18
The End