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VI Single-wall Beam Pipe Option: VI Single-wall Beam Pipe Option: status and plansstatus and plans

M.OlceseM.Olcese

TMB June 6th 2002 TMB June 6th 2002

TMB: CERN June 2002 M.Olcese 2

Double Vs. Single Wall Double Vs. Single Wall DesignDesign

Same Same heaterheater

Same Same outer outer envelopeenvelope

Same Same reflective reflective layer layer (moved (moved outside)outside)

58 mm ID

69.2 mm OD

0.8 mm thick Be tubes

Kapton heater

58 mm ID

0.8 mm thick Be tube Kapton heater

69.2 mm OD

Outer jacket: Aluminized

Kapton

CURRENT DOUBLE-WALL BASELINE PROPOSED SINGLE-WALL DESIGN

4 mm thick passive insulation

Reflective layer: Aluminized

Kapton

TMB: CERN June 2002 M.Olcese 3

ImplicationsImplications

beam pipe design is simpler and less expensivebeam pipe design is simpler and less expensive less material: total % of radiation length of the single less material: total % of radiation length of the single

wall beam pipe 0.49 vs. 0.56 of current baselinewall beam pipe 0.49 vs. 0.56 of current baseline We can get rid of the vacuum pumping line (beneficial We can get rid of the vacuum pumping line (beneficial

impact on services and on the design of ID end plate)impact on services and on the design of ID end plate) beam pipe strength still adequate (see calculations beam pipe strength still adequate (see calculations

presented at the bp review)presented at the bp review) moderate impact on current beam pipe design: we moderate impact on current beam pipe design: we

basically remove the outer wall and the inner wall and basically remove the outer wall and the inner wall and flange design remains unchangedflange design remains unchanged

The aluminized kapton encapsulation might be useful The aluminized kapton encapsulation might be useful to effectively close the pixel Faraday cageto effectively close the pixel Faraday cage

increased axial displacements of the non fixed wire increased axial displacements of the non fixed wire supports and gas seal bellows to be accounted for supports and gas seal bellows to be accounted for

TMB: CERN June 2002 M.Olcese 4

Proposed thermal insulationProposed thermal insulation

Nano-porous Silica Aerogel in flexible quartz Nano-porous Silica Aerogel in flexible quartz fiber carrierfiber carrier

Very low thermal conductivity: 10-12 mW/mK Very low density: 0.09-0.12 g/cm3 Radiation length: 250 cm (worst density) Resistant up to 600 °C Contains: mostly inert materials Si oxides, quartz fibers,

not sensitive to irradiation Can be tailored to specific requirements: carbon

opacified, doped with hydrophobic agents

TMB: CERN June 2002 M.Olcese 5

Thermal Analysis: the Thermal Analysis: the approachapproach

A full simulation of the heat transfer from the heater A full simulation of the heat transfer from the heater through the insulation and the nitrogen gap to the B-through the insulation and the nitrogen gap to the B-layer has been donelayer has been done

All the three heat transfer mechanisms (conduction, All the three heat transfer mechanisms (conduction, convection and radiation) through the gap have been convection and radiation) through the gap have been consideredconsidered

Effect of a beam pipe offset up to a max of 5 mm has Effect of a beam pipe offset up to a max of 5 mm has been analyzedbeen analyzed

Effect of non uniform convective heat transfer has Effect of non uniform convective heat transfer has been estimated been estimated

Assumed boundary conditions:Assumed boundary conditions: Beam pipe bake out temperature = heater temperature = 250 °C Temperature of the B-layer surface = 0 °C (max operating

temperature of B-layer modules)

TMB: CERN June 2002 M.Olcese 6

Average Thermal Average Thermal Analysis: the ResultsAnalysis: the Results

The temperature of the beam pipe surface facing the The temperature of the beam pipe surface facing the B-layer is not an issue: what matters is the heat flux, B-layer is not an issue: what matters is the heat flux, which is determining the B-layer thermal conditionswhich is determining the B-layer thermal conditions

total heat flux to the B-layer is about the 6% of the total heat flux to the B-layer is about the 6% of the nominal capacity of the B-layer cooling system, so it nominal capacity of the B-layer cooling system, so it should be handled with no problemshould be handled with no problem

 

Total out coming heat flux (W/m)Temperature on the outer

surface of the beam pipe

insulation (°C)conduction convection radiation total

No radiation

56 60 0 116 100

Max radiation

34 28 85 147 61

TMB: CERN June 2002 M.Olcese 7

Local effects and Local effects and beam pipe offsetbeam pipe offset

Conduction and radiation are Conduction and radiation are uniform in uniform in , while the convective , while the convective heat flux varies significantly with heat flux varies significantly with his is due to the non his is due to the non symmetric flow pattern in the gapsymmetric flow pattern in the gap

I have found an article on an I have found an article on an experimental study in equivalent experimental study in equivalent conditions (in terms of conditions (in terms of characteristic dimensionless Ra characteristic dimensionless Ra number). The proposed number). The proposed correlations lead in our case to a correlations lead in our case to a max local heat flux 2.6 timesmax local heat flux 2.6 times higher than the average (on the higher than the average (on the top).top).

Other experimental studies show Other experimental studies show that the influence of the beam pipe that the influence of the beam pipe offset up to 5 mm produce a offset up to 5 mm produce a change of both the average and change of both the average and local heat flux of less than 10%local heat flux of less than 10%

The worst case heat flux, The worst case heat flux, which the top B-layer stave which the top B-layer stave will have to dissipate during will have to dissipate during the bake out is 10 W (9% of the bake out is 10 W (9% of nominal cooling capacity)nominal cooling capacity)

conclusion

TMB: CERN June 2002 M.Olcese 8

Thermal Conditions of the Thermal Conditions of the B-layer ModulesB-layer Modules

The major difference between normal operation and bake out is that The major difference between normal operation and bake out is that in normal operation the heat is produced in the electronics while in normal operation the heat is produced in the electronics while during the bake out is coming through the flex during the bake out is coming through the flex

FE-chips and sensor are very well thermally coupled (same FE-chips and sensor are very well thermally coupled (same temperature)temperature)

FE chips

sensor

Flex hybrid

direction of heat flux and temperature gradient during the bakeout

Beam pipe

Carbon-carbon tileCooling channel

TMB: CERN June 2002 M.Olcese 9

Thermal Conditions of the Thermal Conditions of the B-layer Modules, Cont.B-layer Modules, Cont.

There is a stack of thermal impedances from There is a stack of thermal impedances from the module surface and the cooling tubethe module surface and the cooling tube

In normal operation the sensor temperature is In normal operation the sensor temperature is maintained below 0 maintained below 0 °°C with coolant C with coolant temperature of about –20 temperature of about –20 °°CC

during the bake out the temperature gradient during the bake out the temperature gradient between the sensor and the coolant will be far between the sensor and the coolant will be far below (factor of 6), i.e. about 3 below (factor of 6), i.e. about 3 °°CC

The temperature on the flex hybrid (the The temperature on the flex hybrid (the hottest module part) would be about 4 hottest module part) would be about 4 °°C C above the sensor temperatureabove the sensor temperature

The temperature distribution in the b-layer The temperature distribution in the b-layer modules will be almost uniform during the modules will be almost uniform during the bake out: it will be sufficient to keep the bake out: it will be sufficient to keep the coolant T at about –7 coolant T at about –7 °°C to have the whole C to have the whole module below 0 module below 0 °°CC

-7 °°C

-4 °°C

0 °°C

0.7 W/module

TMB: CERN June 2002 M.Olcese 10

Qualification test planQualification test plan

Qualify the Aerogel insulation to our specific Qualify the Aerogel insulation to our specific application. Two parameters to be application. Two parameters to be investigated:investigated:

Radiation hardness in terms of mechanical properties Radiation hardness in terms of thermal properties

Make a full test of the thermal conditions in Make a full test of the thermal conditions in the gap B-layer/beam pipe on a mockup as the gap B-layer/beam pipe on a mockup as close as possible to the proposed solution to close as possible to the proposed solution to validate the thermal analysisvalidate the thermal analysis

TMB: CERN June 2002 M.Olcese 11

Thermal tests on insulation: Thermal tests on insulation: the setupthe setup

Samples to be tested with black Al layer to create a uniform surface

Heated Al Plate

thermocamera

non irradiated sample Irradiated sample

Thick insulating screen

TMB: CERN June 2002 M.Olcese 12

Thermal tests on Thermal tests on insulation: the resultsinsulation: the results

No visible mechanical No visible mechanical degradation after irradiationdegradation after irradiation

Surface temperature Surface temperature difference of about 6 difference of about 6 °°C (4% C (4% of the total of the total T across), small T across), small and might be due to non and might be due to non uniformities material rather uniformities material rather than to the irradiationthan to the irradiation

No surface temperature No surface temperature change after squeezing the change after squeezing the samples with 2 N/cm2samples with 2 N/cm2

• Aerogel sample with polyester fiber carrier and thickness of 2 mmAerogel sample with polyester fiber carrier and thickness of 2 mm• Sample irradiated up to 60 MradSample irradiated up to 60 Mrad

We observedDT across the insulation = 170 °C

The material is mechanically radiation hard (although we tested the polyester The material is mechanically radiation hard (although we tested the polyester carrier type, more sensitive than quartz) carrier type, more sensitive than quartz)

The thermal conductivity might be not affected at all or only marginally by the The thermal conductivity might be not affected at all or only marginally by the irradiation and by a possible accidental pressure on the insulationirradiation and by a possible accidental pressure on the insulation

we conclude

TMB: CERN June 2002 M.Olcese 13

Thermal tests on real Thermal tests on real scale mockup scale mockup

Same beam pipe geometrySame beam pipe geometry Proposed insulation with aluminized kapton Proposed insulation with aluminized kapton

encapsulationencapsulation Dummy B-layer cold structureDummy B-layer cold structure

Tube cooled and maintained at a T = 0 °C

Insulating plugBeam pipe with heater and insulation

During the bake out we want to measure:During the bake out we want to measure: the total heat flux going through the gap to the B-layer The temperature distribution on the outer surface of the

insulation (this can then be correlated to the local heal flux)

1000 mm

TMB: CERN June 2002 M.Olcese 14

Next stepsNext steps

validate the calculations on a real scale prototype (end validate the calculations on a real scale prototype (end of June beginning of July)of June beginning of July)

check the radiation hardness of silica aerogel with check the radiation hardness of silica aerogel with quartz fiber carrier and at higher doses: end of June, quartz fiber carrier and at higher doses: end of June, but need to check where and what sourcebut need to check where and what source

Verify feasibility of kapton encapsulation (ongoing Verify feasibility of kapton encapsulation (ongoing discussion with the beam pipe group: seems not to a a discussion with the beam pipe group: seems not to a a problem)problem)

Study design changes to be incorporated in the Study design changes to be incorporated in the current baseline: redesign the support collars, assess current baseline: redesign the support collars, assess the design impact on the wire supportsthe design impact on the wire supports