Jan. 6, 2006 Chamber & Bellows IDR 1 LCLS Undulator Bellows Module Soon-Hong Lee Internal Design Review

Jan. 6, 2006 Chamber & Bellows IDR 2 Layout General Requirements Specifications Conceptual Designs Materials for Bellows Module FE Stress Analysis Mechanical Failure Test Conclusions Contents

Jan. 6, 2006 Chamber & Bellows IDR 3 Layout Short Break Diagnostic Section

Jan. 6, 2006 Chamber & Bellows IDR 4 From 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 Requirements Bellows motion requirements

Jan. 6, 2006 Chamber & Bellows IDR 5 General Requirements Mechanical Concept of Bellows Module Consider axial travels/constraints for easy installation and maintenance Consider lateral offset with flexible contact fingers and static stub Consider maintenance cycle and material fatigue life Consider mechanical restraints to prevent damages for bellows and fingers RF Connections Provide a sliding surface with good lubricity and good electric conductivity RF fingers, spring fingers, and stub mechanism RF seal ring or spring gasket across flange joints 0.4 ~ 0.5 mils silver plating on the shield fingers 0.2 ~ 0.3 mils rhodium plating on the stub

Jan. 6, 2006 Chamber & Bellows IDR 6 Specifications Flexibility 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) LifeAt least 2,000 cycles Vacuum1 x 10 –7 Torr Low Beam ImpedanceElectric continuity by RF fingers and RF seal ring or spring gasket across flange joint Space ConstraintsMinimize beam directional overall length of module (Z-axis) Axial constraint mechanism for easy installation and maintenance Thermal Loads Bake at 200  C and Operation Heating Contact Resistance Heating Structural LoadsFatigue stress due to flexible strokes across the module Gravity, vacuum force, and contact force Plating Requirements0.4 ~ 0.5 mils Silver plating on the RF-shielding fingers 0.2 ~ 0.3 mils Rhodium plating on the Stub tube/Spring fingers

Jan. 6, 2006 Chamber & Bellows IDR 7 Bellows Module Removable tie rods for restraints to prevent damages Welded Bellows ( 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

Jan. 6, 2006 Chamber & Bellows IDR 8 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

Jan. 6, 2006 Chamber & Bellows IDR 9 Materials for RF Fingers and Stub FingersStub Tube Fingers Flange Need Heat Treatment after forming

Jan. 6, 2006 Chamber & Bellows IDR 10 RF Finger Stress Analysis 3 mm at tip

Jan. 6, 2006 Chamber & Bellows IDR 11 RF Finger Stress Analysis MPa at root > Fatigue strength of BeCu (276MPa)

Jan. 6, 2006 Chamber & Bellows IDR 12 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 finger Stub

Jan. 6, 2006 Chamber & Bellows IDR 13 FEA Case Study CaseContact RF FingersSpring Finger ThicknessMaximum Displacement Maximum Stress Z-travel ( ± 5 mm ) No. of Fingers Root angle Tip angle No. of Fingers Finger angle 1 Point Contact 1818º8º8º8 45º 0.15mm 3.85 mm225 MPaContracted 2936º16º83.82 mm397 MPaContracted º8º8º83.79 mm226 MPaContracted º8º8º82.87 mm144 MPaExtended 4 Surface Contact 1818º8º8º83.13 mm281 MPaContracted 51818º10º940º3.04 mm304 MPaContracted 61522º10º940º0.30 mm3.38 mm553 MPaContracted 7936º18º940º0.15 mm3.84 mm423 MPaContracted 8, mm6.10 mm221 MPaNo 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

Jan. 6, 2006 Chamber & Bellows IDR 14 Case 1

Jan. 6, 2006 Chamber & Bellows IDR 15 Case 3-1

Jan. 6, 2006 Chamber & Bellows IDR 16 Case 3-2

Jan. 6, 2006 Chamber & Bellows IDR 17 Case 8

Jan. 6, 2006 Chamber & Bellows IDR 18 Case 9

Jan. 6, 2006 Chamber & Bellows IDR 19 RF Fingers 0.15 mm thick 53.5 mm long 16 fingers

Jan. 6, 2006 Chamber & Bellows IDR 20 Spring Fingers 0.15 mm thick 29.5 mm long 8 fingers

Jan. 6, 2006 Chamber & Bellows IDR 21 Bellows Module Assembly

Jan. 6, 2006 Chamber & Bellows IDR 22 Mechanical Failure Test Object of failure test is to prove the part in the following conditions 1.2,000 cycle actuation 2.± 5.0 mm axial travel distance 3.± 2.0 mm lateral offset movement 4.  0.5  of angular stroke 5.Ag- & Rd- plating thickness MaterialsSizePriceVendors StubOFE Cu Tube  ½˝ O.D. x ˝ THK x 1.5˝ LG Copper and Brass Sales OFE Cu Rod  5/8˝ O.D. x 1.5˝ LG FixturesOFE Cu Plate5/16˝ (or 1/4˝) x 12˝ x 72˝ RF- fingers / Spring- fingers BeCu 174-HTThickness: 0.15 mm Width: 35 mm Length: 55 mm 1lb/ free sample Brush Wellman, Inc. (1 lb free, $500 min. lot charge) BeCu 25-1/2HT GlidCop A-15Spot Welding Consultant, Inc. $ / min. 5 lb J. L. Anthony & Company BellowsStainless Steel 347 P/N: EE Lateral offset: ±0.17˝ (4.3 mm) Angular offset: ± installed length of 1.59˝ $ /Ea Standard Bellows Company

Jan. 6, 2006 Chamber & Bellows IDR 23 Conclusions Established 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.

Jan. 6, 2006 Chamber & Bellows IDR 24 RF Fingers and Stub Plating Bellows Testing Jim Morgan

Jan. 6, 2006 Chamber & Bellows IDR 25 RF Fingers and Stub Plating and Test Requirements Plating Requirements Maintain electric continuity and provide lubricity across the sliding joint ( RF fingers and Stub) during operations Optimize plating performance Avoid galling Minimize loss of plating Avoid loss of plating adhesion (flaking) Testing Parameters for Bellows Assembly and Sliding Joint Test at 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

Jan. 6, 2006 Chamber & Bellows IDR 26 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 required 4. Optimize performance as budget and schedule allow * Curt Besler, Jeffery Berg “High Current RF Shield for PEP-II Vacuum System Expansion Joint” LLNL M.E. Nordby, N. Kurita “Bellows Design for PEP-II High Energy Ring Arc Chambers” SLAC

Jan. 6, 2006 Chamber & Bellows IDR 27 Plating Materials and Initial Thickness RF Fingers – 0.4 to 0.5 mils Ag Stub – 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 Disulfide Nanolube – nested nanoshpere structure Tungsten Disulfide

Jan. 6, 2006 Chamber & Bellows IDR 28 Section Thru Test Fixture Set-up for dynamic axial Testing

Jan. 6, 2006 Chamber & Bellows IDR 29 Enlarged View – Test Fixture Enlarged view

Jan. 6, 2006 Chamber & Bellows IDR 30 Bellows Prototype Schedule

Jan. 6, 2006 Chamber & Bellows IDR 31 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