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1.2 m Stave with Co-cured Facings Using Low Areal Density Fiber

G. Viehhauser (Oxford)C. Haber (LBNL)T. Hurteau, W. Emmet (Yale)R. Rurns, D. Lynn (BNL)Stave Meeting, Oxford, UK, Feb 2012

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New Co-Cure Experiments at LBNL

• 0-90-0 is a better configuration for mechanical performance but curvature issue is more acute (tight bend across cable)

• Have studied co-cure on a curved template, sized to compensate for bend, worked well on a stavelet cable• In the process of co-curing two full cables in this way in order to laminate a full stave• Pre-co-cure metrology complete

Cable co-cured flatCure inside 9.5 inchpipe result

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Facing challenges for stave cutting facings

Twisted/bowed facing. We were not able to hold down on our vacuum fixture for cutting(but our vacuum fixture was poor. Remaking it might work)

Kapton side is flat across CF-to-kapton transition

Targets proved useful when we cut the facings

Different thickness on CF-only side due to kapton cable

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Tear in Facing and Zoomed Look at Ridge

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tm-b2-011 152.4 152.4 139.7 139.7 203.2 152.4 139.7 152.4 152.42 381 368.3 355.6 355.6 381 368.3 355.6 381 3813 317.5 431.8 406.4 381 406.4 381 381 419.1 368.34 533.4 381 381 381 393.7 355.6 381 368.3 368.35 406.4 215.9 177.8 165.1 215.9 152.4 165.1 177.8 177.86 368.3 3817 355.6 3818 177.8 152.4

Approximate measurement locations

Pre-Cut Facing Thickness Measurements

Serial Power Ground return clearly seen on CF side of facing as a raised ridge, but not so much seen in thickness data

Note: All measurements in microns

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New Cut Facing Width

• Previous specification on facings for old 1.3 meter stave was 120 mm minimum, and 120.25 mm maximum, and we achieved this.

• For this stave we specificed 120.5 mm minimum, 121 mm maximum due to difficulty in achieving this we the co-cured facings

• We had also anticipated such a change in tolerance when we redesigned the bracket and the angle of its contact points

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Cutting the facings

• In the end we clamped down the facings and used a straight-edge and razor

• The edge is not so nice but acceptable• In the future would still prefer rotary fine tooth saw and vacuum chuck,

but we ran out of time to make this work

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Cut Facing Widths

Note: facings from LBNL were numbered 1 and 3, not 1 and two

Facing widths (in mm)

One facing was in tolerance, one slightly over. But this was ok because we still have plenty of clearance from jig supports (as well as bracket supports)

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Note that our support design has cf tubes centers spaced 119 mm,If aluminum was more narrow the gluing would be on facing slope

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Gluing the CF Tubes Side Rails

• To keep facing flat this step and all the following glue steps we had to use lead weights to keep the bowed facing flat.

• Bow was mostly in transverse direction

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Post- Gluing the CF Tubes Side Rails—Transverse Bow

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Gluing the Foam-Pipe Assembly

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Pre-Gluing the Honeycomb

Post-Gluing the Honeycomb

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Post-Gluing the Honeycomb—Kapton Side

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Post Final Facing Attachment

• Stave became flatter (measurements to follow)

• 2nd Facing to CF pipes glue attachment was not ideal. Will fix, but will need to improve process in the future

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Weight [grams]

Total Stave Weight 390.4

facing 1 84.7facing 3 84.6cf tubes 18.3Stainless Steel Pipe+Fittings 76.1closeouts 3.4CGL on foam and pipe 15.3foam 50.4honeycomb 25.3hysol 30% BN facing #1 15.6hysol 30% BN facing #3 16.8

projected cf facing weight [g]32

projected bus cable weight53

Stave Component Weights

x 12/10 compare to Tim 12/9.8Weight [g] X0 [g/cm^2] RL [%] RL norm to det [%] RL norm to det [%]

Pipe 106.3 13.9 0.49 0.59 0.60Foam 45.6 43 0.07 0.08 0.08CGL 15 33.4 0.03 0.03 0.04Facings 104.8 43 0.16 0.19 0.19CF Tubes 38.7 43 0.06 0.07 0.07Closeouts 4.2 43 0.01 0.01 0.01Hysol 30.7 42.4 0.05 0.06 0.06Honeycomb 24.7 43 0.04 0.04 0.05

0.00 0.00Total 370 0.89 1.07 1.09

fitings 16.6

new total 386.6

Co-cured 1.2 m Stave Weights Co-cured Facing Component Weights [g]

Previous 1.3 meter stave weights, no kapton bus

• Used lighter ss pipes in co-cured stave. • If directly comparing, main mass

improvement is 40 grams in carbon fiber facings

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4 Point Support Stave Profile, Side 1 and 3

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4 Point Support Stave Profile, Side 3

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4 Point Support Stave Profile, Side 3 (Flattened in Software)

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Co-Cure Stave Thickness Measurements

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Final Thoughts on Assembly with Co-cured Facings

• Possibly would prefer extended transverse bus for constant thickness

• Metallization may be used to indicate cut line

• Twist creates some problems, mostly for holding facing flat during cutting and grinding

• We might prefer a wider bus (see bottom) to create a uniform facing thickness

• We did not really address alignment issues (top facing to bottom, for example).

• However, all of these problems seem manageable and most glue steps were no more difficult than with flat facings and only required more weight (lead bricks) to keep things flat