Undulator Physics Issues Heinz-Dieter Nuhn, SLAC / LCLS October 30, 2007
LCLS Undulator Bellows Module
description
Transcript of LCLS Undulator Bellows Module
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LCLS Undulator Bellows Module
Soon-Hong Lee
Internal Design Review
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LayoutGeneral RequirementsSpecificationsConceptual DesignsMaterials for Bellows ModuleFE Stress AnalysisMechanical Failure TestConclusions
Contents
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LayoutShort Break Diagnostic Section
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From www.flexhose.com
• Baking temperature at ~200 C• Fabrication tolerance of chamber, BPM, Quad. • Longitudinal cradle motion constraint = 3.0 mm• Total axial travel 5.0 mm
• Adjacent two undulators are tilted symmetrically• Angular stroke for bellows module = 2 tan–1 (height change/length between bellows module) • Height change = 2 mm (~2.5) + 2 mm (~2.5) = 10 mm 2 x tan–1 (10/3800) = 0.3• Undulator segment pitch tolerance (rms) = 14 rad • Total angular rotation 0.5
• Adjacent two undulators are tilted and/or in parallel• Quad center manual adjustment range = 2.0 mm • Total lateral offset 2.0 mm
General RequirementsBellows motion requirements
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General RequirementsMechanical Concept of Bellows Module
Consider axial travels/constraints for easy installation and maintenance Consider lateral offset with flexible contact fingers and static stubConsider maintenance cycle and material fatigue lifeConsider mechanical restraints to prevent damages for bellows and fingers
RF ConnectionsProvide a sliding surface with good lubricity and good electric conductivity
RF fingers, spring fingers, and stub mechanismRF seal ring or spring gasket across flange joints
0.4 ~ 0.5 mils silver plating on the shield fingers0.2 ~ 0.3 mils rhodium plating on the stub
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SpecificationsFlexibility Allow 0.5 of Angular Stroke (Pitch and Yaw)
Allow 2.0 mm of Lateral Stroke (X & Y axes) Allow 5.0 mm of Axial Stroke (Z axis)
Life At least 2,000 cycles
Vacuum 1 x 10 –7 TorrLow Beam Impedance Electric continuity by RF fingers and RF seal ring or spring gasket
across flange joint
Space Constraints Minimize beam directional overall length of module (Z-axis)Axial constraint mechanism for easy installation and maintenance
Thermal Loads Bake at 200 C and Operation HeatingContact Resistance Heating
Structural Loads Fatigue stress due to flexible strokes across the moduleGravity, vacuum force, and contact force
Plating Requirements 0.4 ~ 0.5 mils Silver plating on the RF-shielding fingers0.2 ~ 0.3 mils Rhodium plating on the Stub tube/Spring fingers
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Bellows ModuleRemovable tie rods
for restraints to prevent damages
Welded Bellows (200-125-3-EE)
Axial travel: 16~60 mm lateral offset: 4.3 mm
angular offset: 50
EVAC flanges with chain clamps for
space limitation and easy maintenance
RF-connections
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Bellows Module - Exploded
RF Fingers (BeCu 174) with Ag-plating
Stub (OFE Cu) & Spring Fingers (BeCu)
with Rd-plating
RF seal ring or spring gasket
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Materials for RF Fingers and Stub
FingersStub Tube
FingersFlange Need Heat Treatment after
forming
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RF Finger Stress Analysis
3 mm at tip
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RF Finger Stress Analysis
324.8 MPa at root > Fatigue strength of BeCu (276MPa)
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Design Parameters
RF-finger root
RF-finger tip
• To investigate maximum stress at root • contact types (point contact or surface contact) • # of RF-fingers • # of Spring-fingers• shape of fingers to reduce the overlap damage• thickness and length of fingers
Spring fingerStub
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FEA Case Study
Case ContactRF Fingers Spring Finger
Thickness Maximum Displacement
Maximum Stress
Z-travel (± 5 mm )No. of
FingersRoot angle
Tip angle
No. of Fingers
Fingerangle
1Point
Contact
18 18º 8º 8
45º
0.15mm
3.85 mm 225 MPa Contracted
2 9 36º 16º 8 3.82 mm 397 MPa Contracted
3-1 16 20º 8º 8 3.79 mm 226 MPa Contracted
3-2 16 20º 8º 8 2.87 mm 144 MPa Extended
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Surface Contact
18 18º 8º 8 3.13 mm 281 MPa Contracted
5 18 18º 10º 9 40º 3.04 mm 304 MPa Contracted
6 15 22º 10º 9 40º 0.30 mm 3.38 mm 553 MPa Contracted
7 9 36º 18º 9 40º 0.15 mm 3.84 mm 423 MPa Contracted
8, 9 18 - - 0.15 mm 6.10 mm 221 MPa No Spring fingers
• Use Pro/Mechanica - Contact Analysis - Surfaces of fingers & stub are contacted - Applied ±2 mm (Y) for lateral offset, ± 5 mm (Z) for axial travel• Criteria - Maximum Displacement < 8.0 mm - Maximum Stress < 276 MPa (based on fatigue strength of BeCu Alloy 174)
- 2mm
+ 2mm
+ 5 mm
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Case 1
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Case 3-1
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Case 3-2
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Case 8
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Case 9
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RF Fingers
0.15 mm thick 53.5 mm long
16 fingers
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Spring Fingers
0.15 mm thick29.5 mm long
8 fingers
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Bellows Module Assembly
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Mechanical Failure TestObject of failure test is to prove the part in the following conditions• 2,000 cycle actuation
• ± 5.0 mm axial travel distance
• ± 2.0 mm lateral offset movement
0.5 of angular stroke
• Ag- & Rd- plating thickness
Materials Size Price Vendors
Stub OFE Cu Tube ½˝ O.D. x 0.0625˝ THK x 1.5˝ LG Copper and Brass Sales
OFE Cu Rod 5/8˝ O.D. x 1.5˝ LG
Fixtures OFE Cu Plate 5/16˝ (or 1/4˝) x 12˝ x 72˝
RF-fingers / Spring-fingers
BeCu 174-HT Thickness: 0.15 mmWidth: 35 mmLength: 55 mm
1lb/ free sample
Brush Wellman, Inc. (1 lb free, $500 min. lot charge)BeCu 25-1/2HT
GlidCop A-15 Spot Welding Consultant, Inc.
$460.00 / min. 5 lb
J. L. Anthony & Company
Bellows Stainless Steel 347
P/N: 200-125-3-EELateral offset: ±0.17˝ (4.3 mm)Angular offset: ± 50° @ installed length of 1.59˝
$ 271.00 /Ea
Standard Bellows Company
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ConclusionsEstablished design specifications based on physics requirements, maintenance, and installation etc.Conceptual design and drawings are completed.Based on FE analysis (contact analysis) by use of Pro/Mechanica, max. stress on fingers is expected to have 226MPa which shows below fatigue strength (276 MPa) of BeCu Alloy 174.Lubricity and mechanical failure tests are planned to investigate the Rd- & Ag-plating thickness and the performance of RF- & Spring-fingers.
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RF Fingers and Stub PlatingBellows Testing
Jim Morgan
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RF Fingers and Stub Plating and Test Requirements
Plating RequirementsMaintain electric continuity and provide lubricity across the sliding joint ( RF fingers and Stub) during operationsOptimize plating performance
•Avoid galling•Minimize loss of plating•Avoid loss of plating adhesion (flaking)
Testing Parameters for Bellows Assembly and Sliding Joint•Test at 10-7 torr•Allow visual inspection of sliding joint during the test•2000 cycle test•±5mm axial travel (static and dynamic)•±2mm lateral offset (static and dynamic)•±0.5° angular offset
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Approach
1. Plate RF Fingers and Stub with Rd and Ag according to specifications developed for the bellows for the PEP- II High Energy Ring*
2. Test fingers as assembled inside the bellows to insure acceptable performance at operating conditions for 2000 cycles
3. Change coating thicknesses if required4. Optimize performance as budget and schedule allow*Curt Besler, Jeffery Berg “High Current RF Shield for PEP-II Vacuum System Expansion
Joint” LLNLM.E. Nordby, N. Kurita “Bellows Design for PEP-II High Energy Ring Arc Chambers” SLAC
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Plating Materials and Initial Thickness
RF Fingers – 0.4 to 0.5 mils AgStub – 0.2 to 0.3 mils Rd
Plating thickness can be changed to optimize performance. Other possible materials for increased lubricity at the joint include:
Dicronite – impregnated Tungsten DisulfideNanolube – nested nanoshpere structure Tungsten Disulfide
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Section Thru Test FixtureSet-up for dynamic axial Testing
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Enlarged View – Test Fixture
Enlarged view
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Bellows Prototype ScheduleActivity ID Activity description Early start Early finishUN43_00242 Study of Lubrication Coating 05/02/05A 11/30/2005UN43_00243 Proto Mech. Anal. 06/15/05A 11/30/2005UN43_00241 Proto Prelimin Design 07/22/05A 11/30/2005UN43_00245 Test Tooling Design 11/01/05* 11/30/2005UN43_00244 Evaluation of Lubrication Coating 11/22/05* 1/12/2006UN43_00246 Proto Review 1/13/2006 1/30/2006UN43_00247 Proto Final Design 1/31/2006 2/20/2006UN43_00248 Write Bellow Fab Spec 2/14/2006 3/1/2006UN43_00201 Test Equipment Fab & Assy 2/21/2006 4/3/2006UN43_00070 Bid Package-Ag Plated RF Finger Prtp Bel Mod 3/2/2006 3/6/2006UN43_00080 Bid Package-Rh Plated Stub Prtp Bel Mod 3/2/2006 3/6/2006UN43_00090 Bid Package-Tubes Prtp Bel Mod 3/2/2006 3/6/2006UN43_00100 Bid Package- Prtp Bellows Module 3/2/2006 3/6/2006UN43_00120 Bid Process Prtp Bel Mod 3/7/2006 4/10/2006UN43_00130 Procure Ag Plated RF Finger Prtp Bel Mod 4/11/2006 4/12/2006UN43_00140 Procure Rh Plated Stub Prtp Bel Mod 4/11/2006 4/12/2006UN43_00150 Procure Tubes Prtp Bel Mod 4/11/2006 4/12/2006UN43_00160 Procure Bellows Prtp Bel Mod 4/11/2006 4/12/2006UN43_00180 Prototype Bel Mod Award Complete 4/12/2006UN43_00190 RCV: Bellows Prtp Bel Mod 4/13/2006 5/24/2006UN43_00200 Quality Assurance Prtp Bel Mod 5/25/2006 6/1/2006UN43_00220 Measurement and Test Prtp Bel Mod 6/2/2006 6/15/2006UN43_00230 Review and Report Prtp Bel Mod 6/16/2006 6/22/2006UN43_00240 Prototype Bel Mod Testing Complete 6/22/2006
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Bellows Prototype Costs•Material costs from current loaded schedule
•Bellows $ 1,500•Test Equipment $ 4,000•Evaluation of plating $ 3,000•Rh plate stub $ 900•Ag plate fingers $ 3,000•Fabrication of small parts $ 600