EDR-1 December 16/17, 2002 Hans de Vries - 1 Status RF foil RF/vacuum foil Purpose Production...
-
Upload
shania-darcy -
Category
Documents
-
view
212 -
download
0
Transcript of EDR-1 December 16/17, 2002 Hans de Vries - 1 Status RF foil RF/vacuum foil Purpose Production...
EDR-1 December 16/17, 2002 Hans de Vries - 1
Status RF foil
• RF/vacuum foil Purpose
Production methods used
Deformations: static - overpressure
Electrical properties
Coating
Cables
Interference Silicons
EDR-1 December 16/17, 2002 Hans de Vries - 2
RF and vacuum separation foil(1)
• Protect against RF effectsWakefields in Vertex vesselEMI in detectors
• Good conductivity
Why?• Separation extreme-high-vacuum of LHC from
Detector vacuum– (outgassing electronics, cables, NEG coating,…!)
• Stiffness
Physics requirement:• Restrict amount of material
– preferably low-Z (small radiation length)• Thin
• Detectors should overlap– Alignment– Stereo angle
• Complicated shape
EDR-1 December 16/17, 2002 Hans de Vries - 3
RF and vacuum separation foil(2)
Production from foil
Requirements for:• Stiffness• Welding• Thickness• Shape
•Choice of material•Methods to be used
EDR-1 December 16/17, 2002 Hans de Vries - 4
RF foil and Silicons
EDR-1 December 16/17, 2002 Hans de Vries - 5
VELO Overview
EDR-1 December 16/17, 2002 Hans de Vries - 6
Secondary vacuum box
EDR-1 December 16/17, 2002 Hans de Vries - 7
Material data
Material: AlMg3Young's modulus: 70.000 MPaPoisons ratio: 0.33Shear Modulus: 27.3 GPaYield Strength: 80-180 MPaUltimate Strength: 180-260 MPaElectrical conductivity: 1.9x107 ohm-1 m-1
(almost 50% of pure Al)Weldable!
EDR-1 December 16/17, 2002 Hans de Vries - 8
Production of RF foil
– Hot gas forming• Deform at 350°
– Superplastic deformation• Deform at 520°
– One cycle, p 10 bar
• Methods investigated:– Cold formation
• Press- anneal at 420° (or 350 °) - cool- press …– More than 15 cycles, 2 – 100 bar– Two or more molds
– Explosive formation
Time consuming
Uncontrolled
Crystal growth, melting,Vacuum leaks
Formation speed,Temperature
EDR-1 December 16/17, 2002 Hans de Vries - 9
Hot gas forming
EDR-1 December 16/17, 2002 Hans de Vries - 10
Full size foil
Vacuum tight foil from 300 µm AlMg3Buckling in the center toblerones is solvedRibs (2.5mm high) are added at the forward-end to increase the stiffness.
EDR-1 December 16/17, 2002 Hans de Vries - 11
3D measurement set-up
Mesh for 3D machine
-1000
-950
-900
-850
-800
-750
-700
-650
-600
-1600 -1400 -1200 -1000 -800 -600 -400 -200 0
Exploded view
EDR-1 December 16/17, 2002 Hans de Vries - 12
Measurement of one slot
-900
-890
-880
-870
-860
-850
-840
-830
-820
-810
-702 -701 -700 -699 -698 -697 -696 -695 -694 -693
20 x 5 measurement points
EDR-1 December 16/17, 2002 Hans de Vries - 13
3D result for one slot
-818
-830
-841
-852
-864
-875
-887
-694 -697 -701
-84
-83.5
-83
-82.5
-82
-81.5
-81
-81.5--81
-82--81.5
-82.5--82
-83--82.5
-83.5--83
-84--83.5
EDR-1 December 16/17, 2002 Hans de Vries - 14
Projection for one slot
-84.2
-84
-83.8
-83.6
-83.4
-83.2
-83
-82.8
-82.6
-82.4
-82.2
-82
-702 -701 -700 -699 -698 -697 -696 -695 -694 -693
Variation in depth of one slot ± 0.1 mm
EDR-1 December 16/17, 2002 Hans de Vries - 15
Minimum depth along foil
-85
-83
-81
-79
-77
-75
-73
-71
-69
-67
-65
-1600 -1400 -1200 -1000 -800 -600 -400 -200 0
EDR-1 December 16/17, 2002 Hans de Vries - 16
Minima enlarged
-84.4
-84.2
-84
-83.8
-83.6
-83.4
-83.2
-83
-1400 -1200 -1000 -800 -600 -400 -200
Variation in depth for all slots: ± 0.2 mm
EDR-1 December 16/17, 2002 Hans de Vries - 17
Close-up minima
-85
-83
-81
-79
-77
-75
-73
-1000 -950 -900 -850 -800
Position of slots along foil: 0.1 mm
EDR-1 December 16/17, 2002 Hans de Vries - 18
Central region
-86
-84
-82
-80
-78
-76
-74
-72
-890 -888 -886 -884 -882 -880 -878 -876 -874 -872 -870
-86
-84
-82
-80
-78
-76
-74
-72
-820 -815 -810 -805 -800 -795 -790 -785
-808-806
-805-803
-801-695.5
-697.8
-698.8
-699.9
-75.5
-75
-74.5
-74
-73.5
-73Interference Si and rf foil:
• Minimum radius• Saddle point
Variation 0.2 mm
EDR-1 December 16/17, 2002 Hans de Vries - 19
Thickness measurements
Along central beam line: 0.28 0.29 0.27 mm
Largest curvature point: 0.15 mm
0.24 0.27 0.25 0.26 0.30 0.27 0.24 0.27 mm
EDR-1 December 16/17, 2002 Hans de Vries - 20
FEM analysis: input
Input model for the FEMcalculations
EDR-1 December 16/17, 2002 Hans de Vries - 21
FEM analysis: down
10 mbar over pressure in primary vacuum
Maximum deflection 0.88 mmin “floppy part” of foil
EDR-1 December 16/17, 2002 Hans de Vries - 22
FEM analysis: up
10 mbar over pressure in secundary vacuum
Maximum deflection 1.04 mmin “floppy part” of foil
EDR-1 December 16/17, 2002 Hans de Vries - 23
Deflection measurement
EDR-1 December 16/17, 2002 Hans de Vries - 24
FEA for full box (1)
EDR-1 December 16/17, 2002 Hans de Vries - 25
FEA for full box (2)
EDR-1 December 16/17, 2002 Hans de Vries - 26
FEA for full box (3)
EDR-1 December 16/17, 2002 Hans de Vries - 27
FEA for full box (4)
EDR-1 December 16/17, 2002 Hans de Vries - 28
RF foil and Silicons-reinforcements
EDR-1 December 16/17, 2002 Hans de Vries - 29
RF shielding
Frans Kroes has produced a note on
Attenuation of an EM field by AlMg4 screen of 0.2 mm
Conclusion:
Assuming a conductivity of 0.33 of pure Al:
At 1 mm distance to the rf screen:
1.415 x 10-3 V/m
EDR-1 December 16/17, 2002 Hans de Vries - 30
Conductivity
Pure Al = 37 x 106 Ohm-1 m-1
• Measured (accuracy 10%) conductivity of 1 m long 1 cm wide strips of AlMg3:
undeformed = 17 x 106 Ohm-1 m-1
deformed = 11 x 106 Ohm-1 m-1
•45% for undeformed•30% for deformed material
EDR-1 December 16/17, 2002 Hans de Vries - 31
Coating (1)
• The extreme deformation might result in tiny leaks in the material.
• Also a protective layer might be used at the inside of the detector box.
• Apply poly-amide-imide coating– Solution in N-Methyl-2-Pyrrolidone (NMP)– Drying and polymerization at 60º, 150º, 260º and
315º C– Properties like Kapton and Torlon – Good electric insulation– Radiation resistant 30 MGy, strength not changed
• Outgassing properties have been studied
EDR-1 December 16/17, 2002 Hans de Vries - 32
Coating (2)
A thin layer of poly-amide-imide is air brushed on the inside of the foil for electrical protection and to increase vacuum tightness
Effect of the layer:
Leak detectionWith Helium
Before After1.2e-3 3.2e-71.2e-5 7.2e-73.6e-5 5.2e-73.8e-5 2.4e-61.2e-6 3.2e-7
EDR-1 December 16/17, 2002 Hans de Vries - 33
Outgassing (1)
Massspectra of outgassing after 48 hour
0.0E+00
5.0E-13
1.0E-12
1.5E-12
2.0E-12
0 5 10 15 20 25 30 35 40 45 50
Mass [amu]
Ion
Crr
ent
[A.l/
s.cm
^2]
Coated
Aluminum
Outgassing after 48 hour - Coated-Aluminum = 2.6E-09 mbar.l/s.cm 2̂ - Aluminum = 6.5E-10 mbar.l/s.cm 2̂
Outgassing poly-amide-imide coating
EDR-1 December 16/17, 2002 Hans de Vries - 34
Outgassing (2)Contribution in the pressure of the secondary vacuum by out gassing
Seff=500l/s
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
0 1 2 3 4 5 6 7 8 9 10
time [day]
P [
mb
ar]
Coating
Flat Cable
Poly-amide-imide coating: 1.5 m2
Kapton cables: 20 m2
EDR-1 December 16/17, 2002 Hans de Vries - 35
Summary and outlook
• Full size RF/vacuum foil has been obtained– Material: 300 m Al with 3% Mg– Minimal radius 8 mm – Deviations measured: ± 0.3 mm– FEM analysis has been performed– Variations measured for 10 mbar
overpressure– Electrical properties measured