1. SVT Mechanics & Beam Pipe
F. Bosi - M. Massa
INFN-Pisa
on behalf of the SuperB-SVT Group
XI SuperB Workshop - Frascati, December 1-5, 2009
SuperB Workshop IX - Perugia, June 16-20, 2009

2. Outline SVT Mechanics Beam Pipe Work planning
Full micro-channel pixel module
Net micro-channel pixel module
Beam Pipe
Requirements and general considerations
Conductive thermal study
Radiation length
Hydraulics and convective cooling
Structural studies
Work planning
SuperB Workshop IX - Perugia, June 16-20, 2009

3. Full pixel module support
CFRP MICROCHANNEL
Obtained with additive method, gluing side by side single microtube. The hydraulic diameter of the unit microtube is 300 mm, the square thickness is 700 mm .
700 mm
700 mm
Spread microchannel components before assembling
Carbon Fiber Poltrusion
CFRP Module Support assembled
The total radiation length of this kind of module is about 0.28 % X0.
An internal peek tubes 50 mm thick, is used to avoid moisture.
SuperB Workshop IX - Perugia, June 16-20, 2009 3

4. Full pixel module Test Results
tests results performed on to N°2 sample for both micro-channel and tri-channel modules.
Tm=32.9°C
Tm=35.9°C
Module Temperature average vs Specific Power for single side
Module Temperature average vs Specific Power for double side
SuperB Workshop IX - Perugia, June 16-20, 2009 4

5. Full pixel module test results
Cooling test results for microchannel (sensor at °C with 2 w/cm2) matches the thermal specifications !
Thermal-hydraulic test , conducted on several module prototipes, comfirms this results .
SuperB Workshop IX - Perugia, June 16-20, 2009 5

6. Net pixel Module
Net Module is a micro-channel support with vacancy of tubes in the structure, accepting worst cooling performance but with strongly gain in X0
Net Microchannel Module Support
Material of the support structure: ( CFRP + peek tube + Water + CFRP Stiffeners )
SuperB Workshop IX - Perugia, June 16-20, 2009 6

7. Construction Activities
Net Micro-channel Module Support realized with a special gluing Mask.
Module dimensions : width 12.8 mm,
length 125 mm.
Gluing operation with epoxy is partially performed on the mask then completed out the mask under microscope

8. Net pixel modules support
125 mm
First Prototype produced !
Net module mechanical structure:
10 microtube + 5 trasversal comb
Thermal simulation under study……..

9. Net pixel module support
Trasversal comb geometry , th=0.5mm
1.5 mm
Comb obtained by micromilling machine tooling
0.75 mm
0.6 mm
0.75 mm

10. Net pixel module support
Epoxy glue used to fix microtube to
trasversal comb .
Very complicated micropositioning and microgluing work on the positioning and gluing mask!.
Sealing in the hydraulic interface obtained still with epoxy.
C = 0.17 % C0

11. Beam Pipe/Requirements
For preliminary studies we consider a monolithic beam pipe with internal diameter 20 mm, th=1mm and a length of 100 mm.
The material is beryllium with thermal conductivity of 216 W/mK.
The total power consumption is 200 W;
that means a power density (Total power/Internal surface) of W/cm2
The request specification is to have Tmax is: Tmax < 35 °C
(same sensor temperature coming from TFD test).
SuperB Workshop IX - Perugia, June 16-20, 2009

12. Beam Pipe/Conductive Study
Considering a steady-state conduction the Tmax will not satisfy the thermal requirements.
In this simulation the two external transversal cross section (cold ring) have a fixed temperature of 10 °C.
Heat transfer mode: steady-state conduction
Material: Beryllium, th=1 mm
Thermal conductivity: 216 W/mK
Total Power: 200 W (3,18 W/cm2)
Beam Length: 100 mm
Temperature boundary condition: 10 °C on the external cross sections (cold rings).
Tmax = °C
SuperB Workshop IX - Perugia, June 16-20, 2009

13. Beam Pipe/General Considerations
In order to satisfy the thermal requirements we followed this convective cooling design.
Geometry under study for the beam pipe :
Legenda:
Green: External Pipe
Red: Internal Pipe with pillars
Bleu: Micro-channels
Di=20mm
THext: Thickness of external cylinder
THcool: Thickness of micro-channel
THint: Thickness of internal cylinder
The beam pipe is build with two beryllium concentric cylinders with 4 pillars in order to have four micro-channels with coolant .Beam pipe length= 150 mm .
SuperB Workshop IX - Perugia, June 16-20, 2009

14. Beam Pipe/Radiation Length
We studies two beam pipe configurations. The shared characteristic is the beam pipe assembled with two cylinders and four micro-channels (see previous slide).
The differences between the two configurations are the thickness of the pipes and of the micro-channels.
ITEM
UPPER LIMIT
LOWER LIMIT
Thickness (mm)
External Pipe
0.3
0.4
Internal Pipe
Micro-channel (Water included)
0.2
Considering a transversal cross section the total radiation length is:
UPPER LIMIT
LOWER LIMIT
% Co
= 0.35
= 0.44
REMARKS: The value “0.12” is due to the 4 mm layer of gold (common to the two configurations).
(still to be included epoxy coating contribution on the beryllium surfaces in contact with coolant)
SuperB Workshop IX - Perugia, June 16-20, 2009

15. Beam Pipe/Hydraulics Studies
For both configurations we have analyzed the hydraulic and the thermal behaviors,
considering water as coolant and imposing 2 °C as longitudinal thermal gradient (temperature difference between input and output ) we found this characteristics :
UPPER LIMIT
Channel thickness: 0.2 mm
LOWER LIMIT
Channel thickness: 0.3 mm
Hydraulic diameter
0.394 mm
0.578 mm
Flow per row(*)
0.358 kg/min
Reynolds number
865
846.5
Fluid velocity
2.2 m/sec
1.44 m/sec
Distributed pressure losses
0.67 atm
0.2 atm
Nusselt number
5.25
5.122
Average film coefficient
7193 W/m2K
4711 W/m2K
(*): The flow per row is the same for the two cases because they have same specific power, same longitudinal gradient and same specific heat and the definition is:
SuperB Workshop IX - Perugia, June 16-20, 2009

16. Beam Pipe/Convective Studies/1
The inputs and the boundaries conditions are:
Power density: 2.12W/cm2
Coolant: Water
Film Coefficient:
Material: Beryllium
7193 W/m2K for the inferior limit
Thermal Conductivity: 216 W/mK
4711W/m2K for the superior limit
Longitudinal thermal gradient between input and output: 2 °C
Coolant temperature: 10 °C
The results are:
Lower limit
Upper limit
12.7 °C
13.8 °C
REMARKS: In order to simplify the convective calculus we have a typical transversal cross section.
SuperB Workshop IX - Perugia, June 16-20, 2009

17. BP/Convective Studies/2
Upper limit – Internal Pipe
Lower limit – Internal Pipe
12.7 °C
13.8 °C
SuperB Workshop IX - Perugia, June 16-20, 2009

18. BP/Convective Studies/3
Upper limit – External Pipe
Lower limit – External Pipe
12.1 °C
12.8 °C
SuperB Workshop IX - Perugia, June 16-20, 2009

19. Beam Pipe/Structural Studies
For the structural studies we have focused our attention to the upper limit layout (beam pipe thickness 0.3mm) .
The internal beryllium beam pipe is a pressure vessel loaded with an atmospheric pressure due to the vacuum and to the pressure due to the the coolant inside the micro-channels (total value about 1.7 Atm.)
Assuming for the calculus a pressure value of 5 Bar means take about a security factor of 3.
The stress on the beam pipe calculated with elastic criteria results:
Longitudinal stress: kg/mm2
Circumferential stress: kg/mm2
( Very far from the work tension of the beryllium material ! )
SuperB Workshop IX - Perugia, June 16-20, 2009

20. Beam Pipe/Structural Studies
For what concern the elastic instability of the internal beam pipe, a typical failure criteria of thin cylinders is buckling .( Cylinder is thin when the ratio between the thickness and the external diameter is  0.1).
For beam-pipe geometry, we evaluate the value of the critical buckling pressure with the Von Mises* relation and found :
Pcr ≈ 20 atm (critical pressure )
We found this result using a length of 200 mm) (adding a new safety factor in length respect the 150 mm assumed in thermal hydraulic study and considering as a reinforcements an annular brazing ring Be-SS ).
*correction also with Windenburg and Trilling criteria

21. BP/Structural Studies
Studies with no defects are not realistic , for this purpose let’s introduce the terms “” . ( is the deviation from the radius value of ideal cylinder, in other terms is the eccentricity value of radius beam pipe)
If, for construction problems, we assume  = 0.5 mm, the critical pressure caused by buckling is: goes down fr 20 atm to 5 atm.
Pcr- ≈ 5 atm (critical pressure for geometry )
We are taking contact with brush -Wellman company in order to verify technological and manufacturing problem for the beam pipe dimensions .
SuperB Workshop IX - Perugia, June 16-20, 2009

22. Future Works/ Conclusions
Next work on the Net pixel micro-channel support are thermal and hydraulic test at the TFD lab in Pisa , as the ones performed for the full micro-channel module, in order to validate cooling temperature conditions .
For the beam pipe design we want made an aluminum model for the inner central skin. The idea is to test structural and thermal dimensioning for aluminum material and translate then the results on the Beryllium material .
Design of central skin of beam-pipe need to be integrated with transition part Be- SS, brazed joint, cooling beam pipe lines and cooled manifold flanges for L0 support .