Upload
luke-haynes
View
218
Download
1
Embed Size (px)
Citation preview
Dec. 4, 2001 CERN-1 Hans de Vries
• VELO Mechanics RF/vacuum foil
Rectangular bellow
Wake field suppressors
Cabling
• Summary & Outlook
VELO mechanical aspectsVELO mechanical aspects
Dec. 4, 2001 CERN-2 Hans de Vries
Global system designGlobal system design
• Decouple access to Si detectors from access to 1ary vacuum
• Use (ultra)pure neon venting
• NEGs need not be baked after access to Si detector
• Baking up to 150 oC is possible
• Mount two detector halves independently
• Note large-size, rectangular bellows and thin RF screen
2ary vacuum2ary vacuum
1ary vacuum1ary vacuum
airair
Dec. 4, 2001 CERN-4 Hans de Vries
RF and vacuum separation foilRF and vacuum separation foil
Overlapping detectors• stereo angle• alignment
• Separate prim. and sec. Vacuum• Stiffness
• Protect against RF effects• Wakefields• EMC
• Restrict amount of material
Dec. 4, 2001 CERN-7 Hans de Vries
FEA on Al. 250 m
0.25 mm top plate0.5 mm side
plates
15 mbar
max. displacement
0.35 mmmax. stress [MPa]
58.8 MPa
Dec. 4, 2001 CERN-8 Hans de Vries
Aluminum (250 m thick):• FEA: max p 15 mbar irreversible deform., no safety factor • successfully welded 100 m on 300 m• press-shaping developed: superplastic forming of AlMg3• “cheap & readily” available (compared to Be)• Foil can be produced with radius of 6 mm • Sharp edges of detector have to be rounded off
Thin RF/vacuum foilThin RF/vacuum foil
2000 2001
Dec. 4, 2001 CERN-9 Hans de Vries
Superplastic Forming
Aluminium Superplastic Forming (SPF)
Hot stretching process: sheet of superplastic grade aluminium alloy is forced onto or over a single surface tool by the application of air pressure.
Discovered in 1920 (Pb-Zn, Cd-Zn)
not much interest in the West.
1947: sverhplastichnost
http://www.superform-aluminium.com
T = 470 - 520° C
small grain size
bubble or cavity forming
Dec. 4, 2001 CERN-12 Hans de Vries
Latest RF foils
Deformation:32 m at +15 mbar 20 m at -15 mbarCompletely elastic
He leak tested
Concrete mold has been replaced by a brass one
Dec. 4, 2001 CERN-13 Hans de Vries
Explosive Formation
Statement producer:Uniform thickness after deformation.Test will be performed.
Dec. 4, 2001 CERN-15 Hans de Vries
Rectangular Bellow (2)
The diaphragms were cut out of a 0.15 mm stainless steel plate with a laser machine.Next the diaphragms have successfully been shaped in a forming mold.
Dec. 4, 2001 CERN-16 Hans de Vries
Rectangular bellow (3)
The forming mold with the pressure envelope.The pressure envelope is used to keep the system in place.
Dec. 4, 2001 CERN-17 Hans de Vries
Rectangular bellow (4)
With nitrogen at a pressure of 10 bar the diaphragm are deformed into the right shape.
Dec. 4, 2001 CERN-19 Hans de Vries
Rectangular bellow (6)
7 stainless steel plates (0.15 mm) will be vacuum brazed together.
Before brazing, the 0.05 mm Ni-alloy solder is spot welded between the layers.
Dec. 4, 2001 CERN-20 Hans de Vries
• Install wake field suppressors after mounting 2ary vacuum container
• Upstream is “easy”: mounted with large flange off
• Downstream is more delicate: mount through top flanges
• 70 m CuBe, O/C, coated
• Install wake field suppressors after mounting 2ary vacuum container
• Upstream is “easy”: mounted with large flange off
• Downstream is more delicate: mount through top flanges
• 70 m CuBe, O/C, coated
Wake field suppressors (1)Wake field suppressors (1)
Aim:Provide a continuous conducting wall throughout the VELO to guide the mirror charge
Aim:Provide a continuous conducting wall throughout the VELO to guide the mirror charge
Dec. 4, 2001 CERN-21 Hans de Vries
Wake field suppressors (2)
The Wake field suppressor is made of two 0.075 mm thin CuBe foils,compressed with gear wheel and rack. CuBe is chosen for the good electrical and elastic properties. The foil can be hardened at 320 degrees Celsius to get better spring properties.
Dec. 4, 2001 CERN-22 Hans de Vries
Wake field suppressors (3)
New design of the The Wake Field Suppressor, which follows better the contour of the beam pipe..
Dec. 4, 2001 CERN-23 Hans de Vries
Cabling (1)
Almost solidcable tree!
• Cables• Connectors
very expensive!
Dec. 4, 2001 CERN-24 Hans de Vries
Cabling (2)
Cables inside vacuum:• Heat production• Signal shielding
Kapton with 3 Cu layers:• Outer layers for power and ground• Inner layer for signal
Very expensive!New design has been made to optimize nr. of kapton sheets required
Dec. 4, 2001 CERN-26 Hans de Vries
Summary & Outlook
• Base solution for RF/vacuum foil– 300 m base material Al with 3% Mg– 170 m at inner region– Radius 6 mm
• Rectangular bellow– Diaphragms are ready– Will be assembled the coming months
• Wake field suppressors– The wake field suppressors work fine– A new design is in production
• Cabling solution available– Has to be discussed further