Recent Mechanical Barrel Stave Development

1. Recent Mechanical Barrel Stave Development • Current Mechanical Prototypes • Thermal FEA • End Insertion • Measurements of LBNL Stave BNL; S. Duffin, A. Gordeev, D. Lynn, G. Mahler: LBNL; C. Haber, M. Gilchriese: Yale; W. Emmett, A. Martin, P. Tipton

2. BNL/Yale/LBNL Update on Mechanical Barrel Stave Prototypes Prototyping Plan/Schedule Prototype 1. 107 mm x 350 mm composite without tubing Completed Prototype 2. 107 mm x 350 mm composite with tubing Week of Oct13-17 Weeks of Oct24-Nov5 Prototype 3. 107mm x 1350 mm composite with tubing Week of Oct 27-31 Week of Dec 1-6 • Strike-throughs show schedule as presented at MIWG meeting early October. • Start on proto-type 2 delayed due to delay in getting pipe-foam assembly. • Decided to push back prototype 3 so we can first do some thermal tests on prototype 2.

3. Prototype 1 Completed 35 cm x 10.7 cm , 3mm thick honeycomb 3mm honeycomb, rms(thickness)=19 um, min-max=77um Original Honeycomb Glued BN filled Hysol 9396 Magnified view of grinded honeycomb Demonstrated our ability to grind and glue the CF honeycomb

4. Assembly Fixture Prototypes II and III Bracket locations correspond to possible support locations on barrel. Precision located to +/- 25 um. 3 mm OD carbon fiber tube for end insertion Rare earth magnet to attract steel rod Steel bracket to channel magnetic flux and hold CF tube Steel Rod

5. Prototype II • We are in the process of assembling prototype II. • Tube-foam assembly uses stainless steel 2.77 mm OD, 255 um wall stainless pipe • We use poco foam over k-foam as poco foam is more uniform in cell size • Did some brief comparisons between thermal gels for interface, and chose CGL do to its softness. This will be an area of future R&D however • Will apply Hysol 9396 epoxy for bonding between facing and honeycomb/foam. For honeycomb, only apply at points of contact CGL Foam Interface Layup of Prototype II Pocofoam (top) compared to K-foam (bottom)

6. Prototype III Components 90/0/90 CF Facings K13C2U, 1 meter long Hysol 9396 with 30% BN Facing-honeycomb, CGL epoxy Facing-poco foam 2 pcf carbon honeycomb Will grind to 3-5 mm Side tubes for mounting Have 3 or 5 mm OD CF tubes SS Tubing 2.77 mm OD, 2.26 mm ID (255 um walls) Bus Cable Samples provided by LBNL from prototypes for 6 cm stave….will patch several pieces together Dummy Detectors 97 mm x 97 mm Dummy Hybrids Resistors on 99 mm x 25 mm AlN substrate

7. Prototype III • Proto 3 serves will be a 1 meter long stave closer to the present baseline stave. • It is shorter than current basesline (135 cm) because of the limited length of our existing carbon fiber. • We will mount with dummy modules for full thermal and mechanical testing and comparison to simulation. Thermal FEA by Yale, Mechanical at BNL • It may be either a 3 mm or 5 mm thick inner core (foam, honeycomb) stave, depending upon tests and FEA of prototype II. It is difficult to encapsulate 2.77 mm tube with poco foam unless one goes to a thicker foam. We need to understand tradeoff. Prototype IV • Envision making another stave ~ summer 09. Would have full length (~ 1220 mm), custom K13D2U or other facing with low areal density, and with end closeouts (on 117 mm edges). • Before making this we will do R&D into the foam-pipe interface, correct CF facing layout to maximize thermal performance

8. Thermal FEA

9. End Insertion IDEA – Hold stave at those tube locations that were held to an accuracy of +/- 25 um during assembly • Use 4-5 brackets per stave for support (corresponds to 20-25 cm bracket spacing) • Two options for alignment of brackets: • If accuracy of mounting holes on barrel is on the order of +/- 50 um, alignment unnecessary. • Otherwise, end brackets first mounted and adjusted into position for stave to be parallel to Z axis. Universal stave template mounts on end brackets, and is used to align middle brackets.

10. End Insertion-- Bracket Modified design for stereolithographic bracket. • Bracket arms are elastic. Hold stave through compression. • Right arm is fiducial side and is stiffer (flexes ~ 100 um). Left arm flexes ~ 0.5-1mm. • Flexibility absorbs tolerances in bracket mounting. Carbon fiber preliminary design Compression = 5 N, Mass = 7 grams R.L. for 5 brackets/stave ~ 0.05% Modified design for stereolithographic bracket.

11. End Insertion – Demonstration Prototype Four brackets are mounted on original assembly fixture Missing picture here Partial Installation on Two brackets “Installation Tool” is spare two brackets mounted on jig plate After Installation

12. Prototype End-Insertion Stave Flatness/Deformation Measurement Profile of stave is measured on original assembly fixture where it is held by fixture “V” brackets (similar to those shown in prototyping photos). Stave is built to have low deformation Original Data Rotated Data

13. End Insertion Stave on Stereo-lithographic Brackets • Measurements taken first with stave supported with 4 brackets spaced ~ 24 cm apart, then with just two end brackets ~ 96 cm apart • With each support, each edge (~5 mm from side tube rails) of stave’s deformation was measured (technique will be shown in section on LBNL stave). • Deformation with 4 brackets not as good as on assembly fixture, but very good for first attempt. • 2 point measurement demonstrates that stave is “floppy”, but end insertion works fine with 4 brackets.

14. End Insertion, Conclusions and Plan • This method of insertion seems simple and viable as our initial prototype has demonstrated. It is a low mass solution. • Second iteration will improve stiffness and have method to align brackets. This will also be fabricated in stereo lithographic thermoplastic • We will aim to have an end insertion demonstration with proper flatness for stave prototype III in aluminum and/or carbon fiber CF Rod slightly beveled (sanded) to permit low force installation

15. LBNL Stave V Measurements • We performed deformation measurements on the last LBNL barrel stave prototype • Stave properties • Facings are K13D2U, 3-ply • Carbon honeycomb • Stave mounted with dummy bus, dummy detectors, and kapton heaters (to simulate hybrid power load) • Length approximately 35 cm • Technique was to measure stave surface profile nine times. • Room temperature • With coolant at ~ -37 deg-C • With power on heaters equivalent to ¼ Watt per readout chip, strip length ~ 3cm • Bring back to room temperature, repeat steps 1-3, bring back to room temp., repeat 1-3 Each profile measurements consists of five scans 11 mm apart. Each scan is in 1 mm steps

16. BNL Measuring Station • Station can measure height of stave to accuracy of less than 10 um with a pair of displacement measuring layers. • lasers move in stave direction in increments as small as 10 um, but we typically use 1-10 mm for a stave • Chiller provides coolant down to close to -40 deg

17. Stave Support for Measurements Support intended to provide cantilevered support at each end and allow expansion in Z LBNL Stave Prototype

18. 3-D Plot of Stave Using Measured Values Silicon Heater CF Facing Height [mm] Coolant ~ -37 deg-C, no power load 270 mm Position Along Stave[mm] Height [mm] 270 mm

19. Difference Plots Room Temp 1 - Chilled 1 Profile Room Temp 1 – Room Temp 2 Difference [mm] Room Temp 1 - Chilled w/power 1 Profile Room Temp 1 – Room Temp 3 Distance Along Stave [mm]

20. Difference Plots Chilled 1 - Chilled 2 Chilled 1 - Chilled 2 (with power) Difference [mm] Chilled 1 - Chilled 3 Chilled 1 - Chilled 3 (with power) Distance Along Stave [mm]

21. LBNL Stave Measurements • The change in stave shape is small as one chills with coolant ~ -37 C, and then adds power to mimic hybrid heat load. • The repeatability of these measurements is good over the short number of cycles (3) we did. • Results will depend upon support. Ad-hoc method of support was intended to mimic support with brackets spaced ~ 25 cm apart. Will later repeat these measurements with prototype III when improved brackets are available first quarter next year. • We will be adding programmability to chiller to perform many temperature cycles to be performed after which difference plots can be made.