M. Gilchriese SLHC Pixel Local Supports Based on Thermally Conducting Carbon Foam E. Anderssen, M....
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Transcript of M. Gilchriese SLHC Pixel Local Supports Based on Thermally Conducting Carbon Foam E. Anderssen, M....
M. Gilchriese
SLHC Pixel Local Supports Based on Thermally Conducting Carbon Foam
E. Anderssen, M. Cepeda, S. Dardin, M. Garcia-Sciveres, M. Gilchriese, N. Hartman and R. PostLBNL
W. Miller and W. MilleriTi
Henry Lubatti, Gordon Watts, Tianchi Zhao, Dept. of Physics
Colin Daly, Bill Kuykendall, Dept. of Mech. Engr.
University of Washington
May 29, 2008CERN
M. Gilchriese
Outline
• Concepts
• Examples of implementation
• Prototype fabrication and tests
• Foam materials testing
• Mechanical and thermal modeling
• Foam development plans
• Design optimization plans
• Prototype fabrication plans
• Conclusions2
M. Gilchriese
Concept Overview• Thermally conducting, low-density carbon foam as
– Structural material and simultaneously
– For conduction of heat to cooling tube(s)
• Same concept for barrel and disk local supports
• Implementation can differ for inner barrel elements, outer barrel elements and disks but keep basic concept same
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Foam
M. Gilchriese
Outer Layers - Example• “Large” area planar sensors. Conservative module design (similar to current)
4
…
34.8 26.8
Module on back
986mm
38.4
CARBON FOAM
M. Gilchriese
Inner Layers - Examples• Monolithic structures
– R 4 cm only
– Modules one side
– Modules alternate sides
• Single-sided staves– R 4 cm
– R 10 cm
• Single-chip modules(e.g. 3D)
5 Potential cable location
M. Gilchriese
Disks• Layout with radial and overlap in progress – not trivial
• Modules on both sides of structure as now
• Radial overlap requires offset in Z
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Back modules
Front modules
Module offsetin Z
M. Gilchriese7 VG VG 77
1st Pixel Prototype “Stave”
Tube with CGL7018
YSH-70 and K13D2U glued to foam
Tube in foam with CGL7018
Allcomp 1 foam
M. Gilchriese
Thermal Results
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0
2
4
6
8
10
12
14
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0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70
P/A(W/cm^2)
De
lta
T a
ve
rag
e
YSH-70 only
K13D2U only
YSH-70 sideHeat both
K13D2U sideHeat both
T does not depend strongly on facing thickness
Note double - side heat not 2 x single – side heating
M. Gilchriese10 VG VG 1010
FEA Model• Heater heat loads, 8.38W
• Silicon heater, 148 W/mK, 0.28mm thick
• Silicon heater adhesive, SE4445, 0.6 W/mK, 0.004in thick, two places
• YSH70 open cloth fabric, one layer, 0.6 W/mK, 0.14mm
• YSH70 adhesive, 1.55 W/mK, 0.002in
• Foam properties varied, from 6 to 30 W/mK
• Al cooling tube, 180 W/mK, 2.8mm OD and 2.19mm ID
• Water, convective film coefficient, 66,000 W/m2K, 1.0L/min– Set 20.25ºC on inner tube wall
• K13D2U facing, 1 W/mK, 0.28mm thick
• K13D2U adhesive, 1.55 W/mK, 0.002in thick
M. Gilchriese11
FEA Thermal Solutions
Double heater Single heater
Agrees with direct measurement of foam(K = 5.8) within understanding of component K values
M. Gilchriese12
Additional Prototypes• Identical width, thickness and adhesives to older prototype
(Allcomp 1) but shorter in length (7.4 cm).
• YSH-70 facings on both sides.
• Heater only on one side. Compare at 0.63 W/cm2
• IR and water flow same as older prototoype ( 1.0 l/min)
M. Gilchriese
Thermal Results
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Foam (g/cc) K(W/m-K) Tave/W
Allcomp 1 0.18 ~ 6We measured
~ 1.2
Allcomp 2 0.21 Not known ~ 1.0
POCO 0.09 ~ 17(z)
~ 6(x-y)Vendor supplied
~ 1.3
Koppers 0.21 ~ 30(z?)Vendor supplied
~ 1.0
B-layer and L1 – recent cooling tests
• First results quite encouraging
• Work with companies to up K and keep low
• SBIR with Allcomp just starting
• Koppers making samples with goal of • POCO already there at sample basis but fragile
Note that production batch e.g. Koppersis 150,000 – 200,000 cm3. An outer staveis 125-250 cm3 (depends on coolant, width)
Present detector-10C power off
Single-sided W
M. Gilchriese
Foam Materials Testing• Done at U. of Washington
• Preliminary results
• Additional tests with bonded facings to be done at U. Washington and Allcomp
• Practical note – Allcomp foam easier to handle, machine
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Foam (g/cc) E(ksi) G(ksi) Comments
Allcomp 1 0.18 15 6 0.27 Low?
Allcomp 2 0.21 150 53 0.43
POCO 0.09 4-8 - - Sample too small
Kfoam 0.21 40 17 0.17
M. Gilchriese
Thermal Modeling• Structure models – fix tube wall T
• Thermal runaway – just started
• Example of outer stave concept T depends on foam K
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H=6000W/m2K (CO2)
T(fluid)=-34ºC @ inlet
Detector peak ~ -24.7ºC
Coolant film ΔT=3ºC
M. Gilchriese
Thermal Runaway
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• Estimates of sensor heating (too simple, must be updated)
• Part of optimization….see later
T in CPixel
@16 cmPixel
@21 cmPixel
@1e16
-35 0.003 0.002 0.017
-30 0.006 0.004 0.033
-25 0.011 0.008 0.061
-20 0.020 0.015 0.113
-15 0.036 0.026 0.203
-10 0.064 0.046 0.356
-5 0.110 0.080 0.614
0 0.187 0.135 1.037
-30
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
-40 -35 -30 -25 -20 -15 -10 -5 0
Coolant Tube Inner Wall Temperature-(C)
Pea
k S
enso
r T
emp
erat
ure
-(C
)
no surface heating1.87mW/mm2 @ 0 C10.67mW/mm2 @ 0 C
W/cm2 vs temperatureAssumes 280 micron fully depleted silicon operating at 600V….too simplistic
Note 3D sensors @100V morelike “16 cm” column
Foam K=6 W/mK
M. Gilchriese
More Thermal • Outer stave
– Variations – see plot– Note that these results also apply to
single-chip wide stave – Needs detailed optimization
• Monolithic designs– Not as well studied– Depends on number of tubes– For one tube per module about
same as stave– For fewer….need colder
170.6 W/cm2 Differential from sensor to coolant wall is 10.6˚C
-35
-30
-25
-20
-15
-10
-5
0
5
10
-35 -30 -25 -20 -15 -10 -5 0Coolant Tube Inner Wall Temperature-(C)
Pe
ak
Se
ns
or
Te
mp
era
ture
-(C
)
baseline foam 6 W/mK
foam=15W/mK
foam=15W/mK, CC=250/25/250
foam=15W/mK, Cable=200W/mK
M. Gilchriese
“Disk” Model• Single tube per 4-chip module – interest in differences, will do
2 tubes later
• Issue is addition of step of foam
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Flex circuit
Flex circuit
Sensor
SensorChips
Chips
Foam
Foam
Carbon fiber
Epoxy
Kapton cable and glue layers – not present in disk but for comparison with stave
M. Gilchriese
“Disk” Model Thermal Results
• Remember single tubesingle tube Tmax (no sensor heating)
• Difference in T for module on step is small 1C or less => foam step is viable option for disks.
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Cable layer removed. Foam has k = 6 W/mK. Peak temperature is 21.5 C above the coolant.
Facing Foam
In-plane K Transverse K K T
6 21
10 16
15
600 20 6 17
600 20 10
600 20 15
M. Gilchriese
Mechanical Analysis Examples
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Gravity sag <5 microns
Thermal distortion < 10 microns
Gravity sag < few microns for rigid 5-point support
Thermal distortion 50 microns
All very preliminary. Needs much more work along with support structure design
M. Gilchriese
Foam Development• Note that Allcomp foam is different than
graphite foams from POCO or Koppers
• POCO and Koppers interested, Koppers making low density samples for us to test
• Allcomp foam uses RVC (reticulated vitreous carbon) foam as base and adds high thermal conductivity material to ligaments in the RVC foam
• Allcomp has just received special funding to develop foam for HEP application
• Make and test samples of different density, porosity, heat treatment, etc
• Make stave-like test structures and measure mechanical & thermal performance
21
Allcomp foam
3in by 6in by 2in thickness block100 ppi and 0.12 g/cc
M. Gilchriese
Design Optimization• In the next few months we want to explore quickly a wide range of
design options based on foam concept– Meet thermal requirements(based on sensor heating update to appear soon).
Calculate thermal runaway (obviously depends on coolant assumed)– Some mechanical input(for material estimates)
– Minimize materialMinimize material
• Span many (all?) options– Tube types – Aluminum, carbon fiber, stainless, CuNi – and number of tubes
per module(1 every 2 cm width or can we do better..)
– Facing materials – none (just glue), fiber, carbon-carbon, TPG, diamond– Foam combinations
• All one density and K• Mix low density and higher density
– Overall design optimum(or optima) for different regions(inner, outer, disk)
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M. Gilchriese
Prototype Fabrication• Follows design optimization
• Also depends on choice of coolant and when choice is made
• Coolant path– Choice of coolant is critical
– Prototype “stave” sent to CPPM for tests
– Hope to establish CO2 capability in US relatively soon
• Continue to make very small prototypes for foam characterization
• Number and type of small prototypes depends on design optimization studies – what makes sense
• Ambitious goal would be to build full-length prototype outer stave by early 2009 based on design and small prototype studies.
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M. Gilchriese
Conclusion• Local supports based on thermally conducting carbon foam
continues to look like good idea
• Two immediate next steps– Design optimization, for which a critical assumption is coolant type
– Continue and expand foam development
• Very small and small prototype development (limited mostly by resources)
• Goal would be to build full-length outer stave prototype for thermal and mechanical tests by early 2009. Combine with electrical?
• Note – have ignored implications of B-layer replacement pending Task Force Report.
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