1 / 29

Two Pixel Configurations Under Study

Two Pixel Configurations Under Study. First: A Monolithic Integrated Structure Axial array of six per half structure 21.4mm wide detectors, array of 12 6 cooling passages, double pass 800mm long structure Second: Staves with Supporting Shell Circumferential array of 14 staves

ezekiel-whitley
Download Presentation

Two Pixel Configurations Under Study

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Two Pixel Configurations Under Study • First: A Monolithic Integrated Structure • Axial array of six per half structure • 21.4mm wide detectors, array of 12 • 6 cooling passages, double pass • 800mm long structure • Second: Staves with Supporting Shell • Circumferential array of 14 staves • 16.2mm wide detector, 48 modules per stave • Overall length 778mm VG 1

  2. Integrated Monolithic Structure VG 2

  3. Preliminary Evaluation of Integrated Structure • Salient points • Constraint: stay clear zone around beam pipe • 70mm diameter • Support split into two halves • Requires equal modules around perimeter; for grouping two cooling tubes, inlet and exit same end • Heat load assumption for 800mm length=120W • Two pass for each cooling tube: 5mm ID to limit pressure drop to <200mbar • Issues under study: cooling and structural support for minimum radiation length 37.5mm 24.4mm 88mm VG 3

  4. Integrated Structure (Continued) • Split Structure • Sandwich structure, with cooling tubes embedded between 2-layer composite facing • Composite laminate produced using K13D2U fibers and Cyanate Ester resin • 5mils for two layers (0/90) • 5 mm ID Aluminum tubing, 12 mil wall (~5.6 mm OD) • FEA Structural Model • Tubes and foam core treated as solid elements • Mass of coolant, average density 145kg/m3 • Outer surface laminate: used laminate element, with single material • Inner surface (saw-tooth) contain laminate elements with material designations for: • Composite layers (0/90) • Silicon module assembly, 0.5mm silicon • Cable, 0.9mm uniform along length VG 4

  5. Gravity Sag • Model based on 1G loading vertical • Sag measured in local coordinates • T1: translation is vertical along shell split plane • Maximum sag ~2.8microns • Model length 800mm 2.8μm VG 5

  6. Thermal: 50C Temperature Change • Thermal strain due to cool-down • Local coordinates, T2 is transverse to vertical plane of symmetry • peak shape change is 5.5microns • Model length 800mm Unfortunately the out-plane distortion is a combination of T1 an T2 Y VG 6

  7. Thermal: 50C Temperature Change • Thermal strain due to cool-down • X: direction 8.2 to 6.6 microns • X is split plane, using symmetry boundary conditions • Model length 800mm X-Direction VG 7

  8. Pixel Thermal Solution-Integrated Structure • Description • Isotropic carbon foam: 45W/mK • Specialized low density (0.21g/cc) foam: enhanced to high conductivity • Includes 5mil laminate thickness • Detector 250microns • Chips 200 microns • Bump bonds 25microns • Interface resistance from bonding chip to foam equal to 0.8W/mK; 4mil thickness (CGL7018) • Pixel chip heating: 0.51W/cm2 • Simulated tube wall -22ºC • Results • Peak chip edge: -13.8 ºC • Detector ranges from-15.6 to -17.8 ºC -17.8ºC -15.6ºC Center detector more representative VG 8

  9. Stave Approach VG 9

  10. Staves With Support Shell • Issues • Confined space, need additional room for support shell • Provide stave with 5 point support • Minimize sag and out-of-plane distortion from sub-cooling • Minimize amount of construction material • Combination of high conductivity foam as before in the integrated design • And two layer laminate, uni-tape or single layer of woven cloth • What happens to interfacial stresses • Calculated, but best resolved through testing • Approach thus far • Design layout to compress geometry: inner diameter set at 70mm, outer diameter ? (most likely ~88mm) • Analyze basic stave stiffness and thermal performance VG 10

  11. Initial Layout-Stave 1 • Concept • Retained features of integrated design, same cooling tube size • Less foam, but added cylinder • Outer diameter ~93mm • Inner diameter 70mm VG 11

  12. Stave 1: Basic FEA Configuration • Effects simulated • Mass of coolant, average density 145kg/m3 • Laminate, 2 layers 2.5mil, 0/90, K13D2U • Radiation Length estimate=0.532% • Foam=0.11% • Tube=0.3% • Composite=0.11% • Coolant=0.012% 5.6mm OD tube 12mil wall 5mil laminate 0.5mm of silicon to simulate chips and detector Also 0.9 mm of Kapton cable for additional mass VG 12

  13. Second Configuration-Stave 2 • Goals • Reduce tube size and amount of foam material • Analytically evaluate impact on thermal and mechanical design OD=88 mm ID=~69.75mm VG 13

  14. Stave 2: With Offset Mounts • Space on back-side next to mounts appears adequate to place cable, for wrap-around mounting Cable position (for thermal analysis) Potential cable location VG 14

  15. Stave 2: With Offset Mounts • Cable Illustration • Back side, thin bonding wraps around • Cable on back-side becomes thicker as the stave end is approached Cable constant thickness in this region VG 15

  16. Stave1: Gravity Sag • Upper Stave position near vertical centerline • Modeled ½ length, from mid plane of symmetry of a 778 mm long stave • Model provides effect of a 5 point support stave length • Resulting gravity sag 0.085microns Does not include support shell sag VG 16

  17. Stave 1: Thermal Distortion • Cool-down effect: 50°C Delta • Most of distortion is contraction along stave length • Distortion T2 is out-of-plane • T2 peak distortion is 5.6microns VG 17

  18. Stave 1: Thermal Strain • Stress in Foam/Tube Interface • Evaluated without compliance of bonding adhesive (CGL7018 type) • Contraction of Al tube produces local stress of 300psi at interface • Effect best evaluated through testing • Plan is to use special Reticulated Vitreous Carbon Foam with enhanced thermal and mechanical properties Solid Von Mises Stress VG 18

  19. Stave 2: Gravity Sag • Upper Stave position near vertical centerline • Modeled ½ length, from mid plane of symmetry of a 778 mm long stave • Model provides effect of a 5 point support stave length • Resulting gravity sag 0.41microns Does not include support shell sag VG 19

  20. Stave 2: Gravity Sag-Off Set Mount • Effect on rotation of stave • Maximum rotation 1.9μradians due to sag VG 20

  21. Stave 2: Thermal Distortion • Stave with out-of-plane bending due to cool-down 50°C • Modeled ½ length, from mid plane of symmetry of a 778 mm long stave • Model provides effect of a 5 point support stave length • Resulting bending 51.5 microns VG 21

  22. Stave 2: Thermal Strain • Stress induced by contraction • Less than in Stave 1 geometry • 145psi, more localized at ends • Be mindful that compliance of adhesive not present VG 22

  23. Stave 2: Thermal Solution • Model Parameters • Carbon Foam, 45W/mK • Composite Facing, K13D2U-55% vol fraction • 0/90, Kt=0.55W/mk, 220W/mK planar (no axial thermal gradient so this parameter is not an issue) • Chip 0.2mm • Bump bond thickness, .05mm • Detector, 0.25mm • Adhesives • Tube to foam, 4mils, 0.8W/mK • Foam to composite facing, 2mils, 0.8W/mK • Chip to composite facing, 4mil, 1.29W/mK • Cable to detector module, 2mils, 1.55 W/mK VG 23

  24. Stave 2: Thermal Solution-No Cable • Coolant Tube “BC” • -22ºC • Chip Heat Flux, 0.6W/cm2 • Detector Temperatures • Left edge, -16.66ºC • Middle, -17.01ºC • Right, -16.78ºC VG 24

  25. Stave 2: Thermal Solution-With Cable • Cable heat load • Adds a heat flux of 0.1W/cm2 to the 0.6W/cm2 chip heat load • Gradient before was 4.99ºC, detector middle to tube inner surface • Would expect gradient of 5.82ºC now • Gradient now from detector middle to tube surface is 6.0ºC • Cable surface • Peak -14.1ºC, or a ΔT=7.9ºC • Peak affected by K assumed for the copper/Kapton cable • Used 0.35W/mK, whereas Kapton alone is 0.12 VG 25

  26. Stave 2: Thermal Solution-With Cable • Thermal plot with cable removed • Illustrates comparative uniformity in detector temperature -15.57 -15.94 VG 26

  27. Detector Temperature Summary • Thermal Solutions for two designs, but unfortunately different detector layouts • Integrated, different by chip over-hang • Stave-like, provides complete coverage • Two different foam/sandwich structures, one with less material analyzed first • With time will bring configurations into consistency • However, the predicted detector surface temperature for each is: • Low-mass stave without cable heat load, -17ºC • Low-mass stave with cable heat load, -16ºC • Integrated Foam/Tube Support without cable load, -17.5ºC • Caution, as analysis proceeded slightly more conservative properties were used for the composite facing and the foam: • Facing 0.55W/mK versus 1.44W/mK • Foam 45W/mK versus 50W/mK VG 27

  28. Suggestions for Future Work • Benefits of Continued Analysis • Improve definition of concept • Preliminary results encouraging, but issues will emerge with increased knowledge base • Add support shell deflection, support boundary conditions, end plates etc. • Cooling analysis • Conservatively used 0.6W/cm2 for chip thermal load, revise as electronics design progresses, also expand on cable thermal load (location) • Tube sizing analysis needs more careful consideration • Preliminary pressure drop with smaller tube appears OK with C3F8 • An area that needs more study, pressure drop prediction indicates low margin on return pressure • Consider tube shape change to reduce outer diameter (<88mm?) • Prototyping • Thermal and structural prototypes VG 28

  29. Suggestions for Future Work (Cont.) • Basic Stave Concept uses Lightweight Sandwich • Continued Material development Important to Success • Carbon foam development • Have produced 45W/mK foam • By very nature of HEP goals, heavier than desired • Incentive: Advance through development with carbon nano-tubes additives • Stronger, lighter, more conductive? VG 29

More Related