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


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


RF and vacuum separation foil(2)

Production from foil

Requirements for:• Stiffness• Welding• Thickness• Shape

•Choice of material•Methods to be used


RF foil and Silicons


VELO Overview


Secondary vacuum box


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!


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


Hot gas forming


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.


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


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


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


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


Minimum depth along foil

-85

-83

-81

-79

-77

-75

-73

-71

-69

-67

-65

-1600 -1400 -1200 -1000 -800 -600 -400 -200 0


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


Close-up minima

-85

-83

-81

-79

-77

-75

-73

-1000 -950 -900 -850 -800

Position of slots along foil: 0.1 mm


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


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


FEM analysis: input

Input model for the FEMcalculations


FEM analysis: down

10 mbar over pressure in primary vacuum

Maximum deflection 0.88 mmin “floppy part” of foil


FEM analysis: up

10 mbar over pressure in secundary vacuum

Maximum deflection 1.04 mmin “floppy part” of foil


Deflection measurement


FEA for full box (1)


RF foil and Silicons-reinforcements


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


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


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


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


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


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


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

edr-1 december 16/17, 2002 hans de vries - 1 status rf foil rf/vacuum foil purpose production...

Documents

foil slide

slot slide

temperature slide

vm slide

deformed material slide

deflection measurement

secondary vacuum box

velo overview slide