Alignment and assembling of the cryomodule

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


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


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


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


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


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


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

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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


Dealing with position change between shield and cold mass (posts)


Assembling steps


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;


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


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


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


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


The End

Alignment and assembling of the cryomodule

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