dean r. walters [email protected] april 20, 2006 vacuum chamber review 1 lcls undulator vacuum chamber...
Post on 21-Dec-2015
217 views
TRANSCRIPT
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
1
LCLS Undulator Vacuum ChamberLCLS Undulator Vacuum Chamber
Dean R. Walters
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
2
ContentsContents
Overview
Prototype design
Construction Issues
String Test
Beam Finder Wire
Conclusion
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
4
Prototype Vacuum Chamber Assembly
Results of the Internal Design Review of the Chamber Assembly (Jan. 5, 2006)
The committee was charged with reviewing the design so that construction of the prototype could start.
The conclusions of the committee were that the design and the construction method were thought out enough to support the building of the prototype.
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
5
Single Compound Screw Set-up
Six Compound Screws Set-up
Two Compound Screws Set-upFourteen Compound Screws Set-
up, Full Chamber Mock-up
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
6
Permeability of Stainless SteelsMagnetic Measurements
Type As-received AnnealedAfter
Machining and Forming
Manual TIG
Welding
Final Machining
316 LN 1.003 1.003 1.003 1.004 1.008310S 1.057 1.036 1.033 1.042 1.051
20Cb-3 1.008 1.015 1.015 1.011 1.018Nitronic 33 1.002 1.022 1.03 1.03 1.126Nitronic 40 1.004 1.004 1.005 1.052 1.081
Preliminary Permeability Results
from “Magnetic Properties of Undulator Vacuum Chamber Materials for the Linac Coherent Light Source” by SH Lee presented at FEL2005
Permeability measurement results of 20Cb-3 (Alloy 20) at ANL Central Shops by SH Lee on 4/7/04
Plate: 1.010~1.012 – 19 mm thk (most points 1.010)
Sheet: 1.004~1.006 – 1.5 mm thk (most points 1.005), after correcting for thickness the values are 1.008~1.012 with an average of 1.010.
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
7
Technical ChallengesPolishing – surface roughness
100~200 nm Ra (#8 mirror-finished), securing The physics specification is: For each spatial frequency component of the surface roughness, the ratio of the corresponding spatial wavelength to the amplitude will be greater or equal to 300 over the 0.01-10 mm period range. Structures with periods shorter than 10 µm will be kept smaller at amplitude of less than 25 nm.
Forming – U Channel BendingThe surface in the area of the bend is roughen like an orange peel Tooling design (die/punch) for 12-ft-long forming
Welding Reduction of weld distortion to within straightness toleranceTooling design (welding head motion control) for 12-ft-long weld
Final machining of chamber weldmentWall thickness of 0.5 mm (grinding/milling) – waviness / uniformityGeometric tolerance of flat surface ( 100 m)Controlling the distortion in the XZ plane
Al-coating – thickness/uniformityAbility to perform coating in a small aperture chamber
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
8
Bending of Stainless SteelObject of Tests was to investigate any damages to surface area
With the bending tooling, sample parts were madeV-Block, full-radius, and 1.5 radius female dies – related male punches
To measure the roughness, bent samples were cut by wire-EDMAlso, flat samples were provided to compare the resultsMeasured by MicroXAM RTS surface profiler in the vertical scanning white light interferometry mode.
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
9
Surface Roughness of Bent SamplesObject of Tests was to investigate any damages to surface area
With the bending tooling, sample parts were madeV-Block, full-radius, and 1.5 radius female dies – related male punches
P-V (Å)Sq (Å)P-V (Å)Sq (Å)P-V (Å)Sq (Å)P-V (Å)Sq (Å)
MeasurementObjective
10417818431501352923687138Average
62079126412611839540811205
172682252216869910762321644
103868160815612647825691573
126089213116210899320241132
56272169213725238935281351
50x field of view:
0.244mm
200889273218519791422198185Average
1328892005152109113318361915
1837871916175369415416951934
3177895412193194414918552003
1838951973214214814026841722
1859852356193102013229201701
20x field of view:
0.61 mm
2580120336725620412132790295Average
28171232492225351122021572795
15041093182205156621428483194
31711303517230176722840063083
41811283016275167718121582312
12271104629344168622027803391
5x field of view:
2.44 mm
Flat area / Phase mode
808488708558826577515212072436453252Average
13046595855052166833541318493027625125
6986191435294978305428016186297127714
6575881808078763041167313813038333643
6896278864889360191076113883420537362
69192874446260604814547741256039038781
50x field of view:
0.244mm
Curved area / EX mode
Sample #8Sample #7Sample #6Sample #5
Area measured/instrument mode P-V (Å)Sq (Å)P-V (Å)Sq (Å)P-V (Å)Sq (Å)P-V (Å)Sq (Å)
MeasurementObjective
10417818431501352923687138Average
62079126412611839540811205
172682252216869910762321644
103868160815612647825691573
126089213116210899320241132
56272169213725238935281351
50x field of view:
0.244mm
200889273218519791422198185Average
1328892005152109113318361915
1837871916175369415416951934
3177895412193194414918552003
1838951973214214814026841722
1859852356193102013229201701
20x field of view:
0.61 mm
2580120336725620412132790295Average
28171232492225351122021572795
15041093182205156621428483194
31711303517230176722840063083
41811283016275167718121582312
12271104629344168622027803391
5x field of view:
2.44 mm
Flat area / Phase mode
808488708558826577515212072436453252Average
13046595855052166833541318493027625125
6986191435294978305428016186297127714
6575881808078763041167313813038333643
6896278864889360191076113883420537362
69192874446260604814547741256039038781
50x field of view:
0.244mm
Curved area / EX mode
Sample #8Sample #7Sample #6Sample #5
Area measured/instrument mode
352 nm 207 nm 658 nm 871 nm
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
10
Surface Roughness of Bent SamplesBent sample
(#)Spot location, object
lens, field of viewSq(nm)
(rms)
Sa(nm)
(avg)
P-V (nm) Pictures Remarks
1
Curved area
50 x
0.244 mm2
390 292 6185 1 0.5 mm thick 304 SST, R=1.5
2 1099 867 10560 2 1.5 mm thick 316 SST, R=1.5
3 290 217 3633 3 0.5 mm thick 304 SST, R=2.5
4 908 720 9306 4 1.5 mm thick 316 SST, R=2.5
1
Flat area
2.5 x
4.89 mm2
89 67 845 0.5 mm thick 304 SST, R=1.5
2 78 59 1205 1.5 mm thick 316 SST, R=1.5
3 180 137 2137 0.5 mm thick 304 SST, R=2.5
4 36 26 752 1.5 mm thick 316 SST, R=2.5
1
Flat area
5 x
2.44 mm2
67 56 1434 5 0.5 mm thick 304 SST, R=1.5
2 42 29 3088 6 1.5 mm thick 316 SST, R=1.5
3 71 49 5640 7 0.5 mm thick 304 SST, R=2.5
4 26 19 836 8 1.5 mm thick 316 SST, R=2.5
For each sample, the values shown are average of four measurementsSurface finishes with thinner sheets (0.5 mm) showed better than thicker sheets(1.5 mm).Surface finishes with large bent radius (R=2.5 mm) showed better than small bent radius (R=1.5mm).
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
11
Criteria for Surface Roughness
The wakefield tolerances are chosen such that the resistive wall wakefield dominates the other wakefield components, including surface roughness wakefields and geometric wakefields.
acceptable acceptable300AR
The longitudinal impedance for a circular chamber cross section due to roughness is [1]
222
22 2 2 2, , ,
ˆ81
0
n
ln m n m n m
k s kk i nZ dk
cb n k k k i
[1] G.V. Stupakov, “Surface Roughness Impedance”, SLAC-PUB-8743 (2000)
2
20
1ˆ ,
2ikz in
ns k h z e d dz
This is taken from: Undulator Vacuum Chamber Surface Roughness Measurements and Expected Wakefields
Heinz-Dieter Nuhn, SLAC / LCLSPresented at Physics Meeting on April 13, 2006
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
12
Criteria for Surface RoughnessSample: #8
Mode: PM
Size: 0.244 x 0.244 mm2
Objective: 50x
x’rms: 1.0 mrad; z’rms: 1.1 mrad
x’rms: 2.1 mrad; z’rms: 2.2 mrad
Size: 0.244 x 0.244 mm2
x’rms: 234 mrad; z’rms: 425 mrad
x’rms: 221 mrad; z’rms: 398 mrad
Sample: #8
Mode: EX Objective: 50x
Flat Sample Curved Sample x’rmsand z’rms is a complementary means to express the aspect ratio. The method evaluates the height and the wavelength in terms of an angle that is express in mradians.
In the initial calculations 10.5 mrad is considered acceptable for flat surfaces and 35 mrad for curved.
With these results, work on reducing the roughness in the bend area is continuing.
Besides the work to better cushion the polished surface from the bend dies there is also work on: (1) electro-polish after bending, (2) mechanical polish after bending, and (3) exploring the possibilities that the metallurgical condition of the base material can be altered to improve the surface finish.
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
13
Criteria for Surface Roughness
0 deg
90 deg
Work on the criteria for surface roughness has made progress although there is still a need to extend it. The work shown in previous slides are for a circular cross section chamber whereas the cross section of this chamber design is obround. The curve at right shows the chamber radius in the first quadrant.
Work needs to address the real chamber shape and the limits of practical metal polishing in this confined configuration.
The specification needs to blend the full the allowance from the impedance plus taking into account the chamber shape.
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
14
E2L1.5R300
1 cm/s
E2L2R250
1 cm/s
E2L3R180
1 cm/s
E3L1R400
1 cm/s
1.53 mm
E2.5L2R250
0.8 cm/s
E2.5L2R250
0.9 cm/s
E2.5L2R250
1 cm/sE2.5L2R250
1.2 cm/s
1.53 mm
Laser Weld Test – 316LN SST
E2.5L2R250, 5 J/p, P = 1250W, 1 cm/s, Ar @ 60 scfh
Energy per ms, E (J/ms) = 2~3, Pulse width, L (ms) = 1.5~3 Pulse repetition rate, R
(Hz) =180~400.
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
15
Laser Welding TestWorking with Laser Welding Company to perform welding
They have made initial samplesBelow are examples of two weld joints
Butt Weld with penetration ~2 mm
Lap Weld with penetration ~2.5 mm
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
16
Welding Tasks 1. Work with vendor to determine weld joints and tooling requirements.
2. Design and construct weld tooling
3. Weld prototype chambers
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
17
Coating•Coating Method
•Pulsed Sputter Coating of 99.99% Aluminum onto Stainless Steel substrate
•Substrates are plasma cleaned in Ar prior to coating
•Results of Adhesion Tests•Used Scotch Tape to determine adhesion of film to substrate
•Unable to detach film from substrate even after extreme bending.
•Coating after Fabrication•This insures coverage over all parts including the welds.
•Working with a consultant to work out the apparatus and method for applying the film
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
18
Center Aluminum tube that can be used for plasma cleaning and
coating
1. Coating will now be performed after all the welding and machining are done. The coating tooling will be added to the bake out equipment
2. There are two motivations for revising the coating:
1. Available time on large area planar coating systems is difficult for this batch size, 4 sheets.
2. This solves the problem of coating the strongback and the area of the flange weld area.
3. Adhesion of film is not a strong factor in the characteristics the film.
4. Working with an outside consultant to define process and equipment.
Revised Coating Method
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
19
Work Process of Chamber Prototypes
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
20
Prototype Construction Schedule Activity ID Activity description Early start Early finishUN42_D257 Preliminary prototype design UN chamber 05/02/05A 09/30/05AUN42_D227 Mechanical analysis of chamber 05/02/05A 11/11/2005UN42_DP219 Fabricate Welding Samples and Tooling 05/02/05A 11/30/2005UN42_DR219 Stainless Steel Permeability Testing 05/23/05A 07/29/05AUN42_D220 Perform welding tests 06/13/05A 11/30/2005UN42_DR210 Literature Search - Surface Mesurement 06/14/05A 11/30/2005UN42_D260 Prototype final design UN chamber 09/26/05A 12/22/2005UN42_D223 Final determination of welding process 09/26/05A 1/11/2006UN42_D258 Prototype UN chamber tooling design 11/1/2005 12/7/2005UN42_DR212 Procure surface measurement equipment 12/01/05* 1/19/2006UN42_D259 Prototype design review UN chamber 12/8/2005 12/12/2005UN42_DR218 Design weld tooling 12/13/05* 1/31/2006UN42_DR213 Fabricate surface measuring equipment 12/22/2005 2/9/2006UN42_D261 Prototype design complete 1/31/2006UN42_D262 Bid process prototype UN chamber 2/1/2006 3/7/2006UN42_D263 Bid process prototype UN chamber tooling 2/1/2006 3/7/2006UN42_DR214 Assemble surface measuring equipment 2/10/2006 2/23/2006UN42_DR215 Initial surface test 2/24/2006 3/9/2006UN42_D264 Evaluate bid prototype UN chamber 3/8/2006 3/14/2006UN42_DR216 Test confirmation of surface measurement 3/10/2006 4/6/2006UN42_D265 Procure Prototype undulator chamber (2) 3/15/2006 3/17/2006UN42_D266 Procure Prototype UN chamber tooling 3/15/2006 3/17/2006UN42_D267 RCV Parts prototype UN chamber 3/20/2006 6/12/2006UN42_D222 Final determination of metal surface finish meas 4/7/2006 7/6/2006UN42_DR221 Final determination of metal polishing 4/7/2006 7/6/2006UN42_D268 Quality assurance prototype UN chamber 6/13/2006 6/26/2006UN42_D269 Procure polished parts 7/7/2006 8/3/2006UN42_D270 Fabrication of prototype chamber weldment 8/4/2006 8/24/2006UN42_D271 Measurement and test prototype UN chamber 8/25/2006 9/29/2006UN42_D272 Prototype UN chamber testing complete 9/29/2006
Bid Process started in the first week of
January for the chamber and the supports
Quotes on the supports came in January, delivery
in March
Work is progressing for
a later June 2006
completion
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
21
String Test
Vacuum Test to simulate conductance of small aperture chambers
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
22
Beam Finder WireRendering of Design
This is the mock-up for the SUTThe BFW, support, and connection to
ion pump are shown.
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
23
Beam Finder WireSummation of Bench Test
Upper Aluminum Plate Precision Screw Locking Screw Kinematic Stop Assembly Slide Rod Lower Aluminum Plate Pneumatic Cylinder “Keyence” Sensor “Keyence” Readout (Microns)
Figure 2. Prototype Test Setup
Test results reflect a +/- 5 micron repeatability and an adjustment
resolution of +/- 2 micron.
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
24
Conclusions•Chamber
•The chamber and supports designs have progressed to the point where they are ready for the construction of the prototype.
•The plan is to construct a two chambers.
•One where the U-Channel is made of 316LN stainless steel and the strong-back of 316 SST.
•The other made of 20Cb-3 (Alloy 20) stainless steel, this material can be purchased through domestic suppliers.
•Construction
•Polishing
•Vendor samples have been measured with surface finishes smoother than 25 nm on flat samples..
•Bending
•Samples have been formed into a U shape and the surfaces of some of the samples are smoother than 400 nm. There are also examples that are rougher than what is allowable by the current physics criteria.
•The criteria will need to be expanded for the current chamber shape.
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
25
Conclusions•Construction (continued)
•Welding
•A series of Laser weld tests have been completed and a set of welding parameters have been determined that can yield penetrations up to 2.0 mm.
•Work has begun with a laser welding shop and samples have produced penetrations up to 3 mm.
•Work with the vendor will determine the weld joints and tooling requirements
•Coating
•Aluminum has been sputtered onto stainless steel, that was plasma cleaned, and the strength of the adhesion was great enough to hold the film even on a flexible substrate.
•In order to produce a coating over all internal surfaces, the coating will now be done as a final step after the welding.
•An agreement is being worked for a consultant to aid in the definiation of sputtering process.
•Beam Finder Wire
•Results of the bench test show that the repeatability of placing the wire is ± 5 μm
Dean R. Walters
[email protected] 20, 2006Vacuum Chamber Review
26
Any Questions?
I would like to acknowledge the continuing efforts of: SH Lee, J Bailey, J Morgan, and DS Doran