Vacuum / cryo links Mechanical design issues Jo van den Brand, Martin Doets Nikhef Cascina March 4,

West end Conceptual design Antonio

West input Rotated DN1000 standard valve Options: - small or large link - small link: small or large diameter

West input Short cryo link

West input DN1000 standard valve DN630 standard valve (D = 650 mm) Ion pumps

West input New valve position Valve DN630 Adapter 700 for end stations

West / North end Cold surface: length: 2023 mm diameter: 1000 mm Baffles: diameter: 600 mm 3 needed to cover cold surface temperature influences mirror temperature material: stainless / glass? Mirror

Side view L = 3490 mm D = 1208 mm S.St. 304LReinforcement ribs Hydroformed bellows

Cryo link details LN2 vessel support Baffle D= 620 mm 3.2 mm/m Heat bridge/expansion bellows superinsulation LN2 (200 l)

Transfer line connections 34 mm 60 mm LN2 max level (control ± 10 mm) Bath width: 325 mm Rapid heatup LN2 inlet duct

Phase separator 2 m above cryo link

Performance Expected water load: mbar l/s – Q 1 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 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 phase10 kEuro – Design & engineering45 kEuro – Short link 125 kEuro x 4 Standard phase separator Simple LN2 extraction Simplification of separation rings for LN2 circuit – Valve DN kEuro x 4 ex VAT ex 7.5% discount – Other items75 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 1 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