Vacuum / cryo links

Mechanical design issues

Jo van den Brand, Martin DoetsNikhef

jo@nikhef.nl martind@nikhef.nl Cascina, January 21, 2010

West end

Conceptual designAntonio (March, 2009)

West input

Rotated DN1000 standard valve

Options: - small or large link: small is baseline - small link: small or large diameter, length

West input

Short cryo link

DN630 standard valve (D = 650 mm)

DN1000 standard valve

Ion pumps

West input

Valve DN630

Adapter 700 for end stations

West / North end

Cold surface: length: 2060 mm diameter: 900 mm

Q3: Baffles layout?: diameter: 600 mm ? 3 needed to cover cold surface? temperature influences mirror temperature material: stainless / glass?

Mirror

Q2: prefer smaller diameter Q4: layout different for input and end links

Top view

L = 3490 mmD = 1208 mm

S.St. 304L Reinforcement ribs

Hydroformed bellows

End view and cross section

Side viewSpace for baffles

1100

Baffles not drawn

Side view

Design detail: suspensions

Movable part

Fixed part (to rib / vessel)

Rib

LN2 tests

S.St. 304L vessel50 x 50 x 5 cm3

Isolated by 20 cm foamAverage heat leak 50 W/m2(similar to radiation load on surface with emissivity of 0.1)

Evaporate ~1 l/hourMeasured acoustic noise (~60 dB, 0.02 Pa)

Performance• Expected water load: 10-4 mbar l/s

– Q1 year = 3150 mbar l gas– 22,400 mbar l = 1 mol = 18 gram– Thus, expected load 0.14 mol or 2.5

gram water• Expected layer

– Length 2.0 m, diameter 1 m, Area = DL

– Number of sites 1015 cm-2

– After 1 year expect 0.4 micron layer• Heat load and LN2 consumption

– Depends on emissivity 0.1 – 0.2 – Heat load 200 – 300 W

• LN2 consumption: 3.5 liter/hour• Expected gas load: 0.2 liter/s

Logistics• Quotations: total 789 kEuro (939 kEuro including VAT)

– R&D phase 10 kEuro– Design & engineering 45 kEuro– Short link 125 kEuro x

4• Standard phase separator• Simple LN2 extraction• Simplification of separation rings for LN2 circuit

– Valve DN630 39.8 kEuro x 4• ex VAT• ex 7.5% discount

– Other items 75 kEuro• Valve DN100• Turbo molecular pump station• Gauges, control, tubing, etc.

• Manpower ~ 5 fte– Mechanical and control system design– Construction of (support) structures, etc– Testing– Installation

Summary• Preliminary design for short cryo links

– Length 2.0 m, diameter 0.9 m– Capacity > 1 year for 1 micron layer– Reduced heat load: 200 – 300 W

• LN2 consumption: 3.5 liter/hour• Low gas load (0.2 liter/s), less bubbles, less noise

– Thermal effect on mirrors acceptable– Reduced cost

• Test set-up– Operations

• External vs closed loop condensor• Consumption versus coverage (emissivity development)• Control issues (normal running, regeneration, …)

– Bubble induced noise

Next Steps

• Optical interfaces are being defined = trap length and diameter . Towers position in May/June, the explicit approval on diameter is expected in shorter time

• Trap design is being optimized vs bubbling noise • The order of the first trap (prototype) shall be

shifted in the second half of 2010, without affecting the milestone ‘completion’ of Nov2012.