Dean R. Walters [email protected] April 20, 2006 Vacuum Chamber Review 1 LCLS Undulator Vacuum Chamber Dean R. Walters

Dean R. Walters

[email protected] 20, 2006Vacuum Chamber Review

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LCLS Undulator Vacuum ChamberLCLS Undulator Vacuum Chamber

Dean R. Walters

Dean R. Walters


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ContentsContents

Overview

Prototype design

Construction Issues

String Test

Beam Finder Wire

Conclusion

Dean R. Walters


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OverviewOverview

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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


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Single Compound Screw Set-up

Six Compound Screws Set-up

Two Compound Screws Set-upFourteen Compound Screws Set-

up, Full Chamber Mock-up

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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.

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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

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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.

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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


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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).

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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

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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


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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.

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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


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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

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Welding Tasks 1. Work with vendor to determine weld joints and tooling requirements.

2. Design and construct weld tooling

3. Weld prototype chambers

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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

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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

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Work Process of Chamber Prototypes

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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


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String Test

Vacuum Test to simulate conductance of small aperture chambers

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Beam Finder WireRendering of Design

This is the mock-up for the SUTThe BFW, support, and connection to

ion pump are shown.

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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.

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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.

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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


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Any Questions?

I would like to acknowledge the continuing efforts of: SH Lee, J Bailey, J Morgan, and DS Doran

Documents

Dean R. Walters [email protected] April 20, 2006 Vacuum Chamber Review 1 LCLS Undulator Vacuum Chamber Dean R. Walters