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 effects Wakefields in Vertex vessel EMI 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:AlMg3 Young's modulus: MPa Poisons ratio:0.33 Shear Modulus:27.3 GPa Yield Strength: MPa Ultimate Strength: MPa Electrical conductivity:1.9x10 7 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 AlMg3 Buckling in the center toblerones is solved Ribs (2.5mm high) are added at the forward-end to increase the stiffness.

EDR-1 December 16/17, 2002 Hans de Vries D measurement set-up Exploded view

EDR-1 December 16/17, 2002 Hans de Vries - 12 Measurement of one slot 20 x 5 measurement points

EDR-1 December 16/17, 2002 Hans de Vries D result for one slot

EDR-1 December 16/17, 2002 Hans de Vries - 14 Projection for one slot Variation in depth of one slot ± 0.1 mm

EDR-1 December 16/17, 2002 Hans de Vries - 15 Minimum depth along foil

EDR-1 December 16/17, 2002 Hans de Vries - 16 Minima enlarged Variation in depth for all slots: ± 0.2 mm

EDR-1 December 16/17, 2002 Hans de Vries - 17 Close-up minima Position of slots along foil: 0.1 mm

EDR-1 December 16/17, 2002 Hans de Vries - 18 Central region Interference 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: mm Largest curvature point: 0.15 mm mm

EDR-1 December 16/17, 2002 Hans de Vries - 20 FEM analysis: input Input model for the FEM calculations

EDR-1 December 16/17, 2002 Hans de Vries - 21 FEM analysis: down 10 mbar over pressure in primary vacuum Maximum deflection 0.88 mm in “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 mm in “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: x V/m

EDR-1 December 16/17, 2002 Hans de Vries - 30 Conductivity  Pure Al = 37 x 10 6 Ohm -1 m -1 Measured (accuracy 10%) conductivity of 1 m long 1 cm wide strips of AlMg3:  undeformed = 17 x 10 6 Ohm -1 m -1  deformed = 11 x 10 6 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 detection With Helium BeforeAfter 1.2e-33.2e-7 1.2e-57.2e-7 3.6e-55.2e-7 3.8e-52.4e-6 1.2e-63.2e-7

EDR-1 December 16/17, 2002 Hans de Vries - 33 Outgassing (1) Outgassing poly-amide-imide coating

EDR-1 December 16/17, 2002 Hans de Vries - 34 Outgassing (2) Poly-amide-imide coating:1.5 m 2 Kapton cables:20 m 2

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