LCLS Undulator Bellows Module Internal Design Review SoonHong

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

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

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

General Requirements Bellows motion requirements • 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 and/or in parallel • Quad center manual adjustment range = 2. 0 mm • Total lateral offset 2. 0 mm From www. flexhose. com Jan. 6, 2006 Chamber & Bellows IDR • 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 4

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 5

Specifications Flexibility Life Vacuum 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) At least 2, 000 cycles 1 x 10 – 7 Torr Low 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 Structural Loads Plating Requirements Jan. 6, 2006 Chamber & Bellows IDR Bake at 200 C and Operation Heating Contact Resistance Heating Fatigue stress due to flexible strokes across the module Gravity, vacuum force, and contact force 0. 4 ~ 0. 5 mils Silver plating on the RF-shielding fingers 0. 2 ~ 0. 3 mils Rhodium plating on the Stub tube/Spring fingers 6

Bellows Module EVAC flanges with chain clamps for space limitation and easy maintenance Removable tie rods for restraints to prevent damages Welded Bellows (200 -125 -3 -EE) RF-connections Axial travel: 16~60 mm lateral offset: 4. 3 mm angular offset: 50 Jan. 6, 2006 Chamber & Bellows IDR 7

Bellows Module - Exploded RF Fingers (Be. Cu 174) with Ag-plating Stub (OFE Cu) & Spring Fingers (Be. Cu) with Rd-plating RF seal ring or spring gasket Jan. 6, 2006 Chamber & Bellows IDR 8

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

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

RF Finger Stress Analysis 324. 8 MPa at root > Fatigue strength of Be. Cu (276 MPa) Jan. 6, 2006 Chamber & Bellows IDR 11

Design Parameters • 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 RF-finger root Stub Jan. 6, 2006 Chamber & Bellows IDR Spring finger RF-finger tip 12

FEA Case Study + 2 mm + 5 mm - 2 mm RF 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 Be. Cu Alloy 174) Spring Finger Maximum Displacement Maximum Stress Z-travel (± 5 mm ) 3. 85 mm 225 MPa Contracted 3. 82 mm 397 MPa Contracted 3. 79 mm 226 MPa Contracted 8 2. 87 mm 144 MPa Extended 8º 8 3. 13 mm 281 MPa Contracted 18º 10º 9 40º 3. 04 mm 304 MPa Contracted 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 Case Contact No. of Fingers Root angle Tip angle No. of Fingers 18 18º 8º 8 9 36º 16º 8 16 20º 8º 8 3 -2 16 20º 8º 4 18 18º 18 1 2 3 -1 5 6 Point Contact Surface Contact Jan. 6, 2006 Chamber & Bellows IDR - Finger angle Thickness 45º 0. 15 mm - 13

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

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

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

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

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

RF Fingers 0. 15 mm thick 53. 5 mm long 16 fingers Jan. 6, 2006 Chamber & Bellows IDR 19

Spring Fingers 0. 15 mm thick 29. 5 mm long 8 fingers Jan. 6, 2006 Chamber & Bellows IDR 20

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

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 Materials Size Price OFE Cu Tube ½˝ O. D. x 0. 0625˝ THK x 1. 5˝ LG OFE Cu Rod 5/8˝ O. D. x 1. 5˝ LG Fixtures OFE Cu Plate 5/16˝ (or 1/4˝) x 12˝ x 72˝ RFfingers / Springfingers Be. Cu 174 -HT Thickness: 0. 15 mm Width: 35 mm Length: 55 mm Stub Bellows Be. Cu 25 -1/2 HT Copper and Brass Sales 1 lb/ free sample Glid. Cop A-15 Stainless Steel 347 Jan. 6, 2006 Chamber & Bellows IDR Vendors Brush Wellman, Inc. (1 lb free, $500 min. lot charge) Spot Welding Consultant, Inc. P/N: 200 -125 -3 -EE Lateral offset: ± 0. 17˝ (4. 3 mm) Angular offset: ± 50° @ installed length of 1. 59˝ 22 $460. 00 / min. 5 lb J. L. Anthony & Company $ 271. 00 /Ea Standard Bellows Company

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 226 MPa which shows below fatigue strength (276 MPa) of Be. Cu 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 23

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

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 10 -7 torr • Allow visual inspection of sliding joint during the test • 2000 cycle test • ± 5 mm axial travel (static and dynamic) • ± 2 mm lateral offset (static and dynamic) • ± 0. 5° angular offset Jan. 6, 2006 Chamber & Bellows IDR 25

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 26

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 27

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

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

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

Bellows Prototype Costs • Material costs from current loaded schedule Jan. 6, 2006 Chamber & Bellows IDR • Bellows $ 1, 500 • Test Equipment $ 4, 000 • Evaluation of plating $ 3, 000 • Rh plate stub $ • Ag plate fingers $ 3, 000 • Fabrication of small parts $ 600 31 900