Vacuum / cryo links Design issues Jo van den Brand, Martin Doets Nikhef Cascina Feb. 3,

West end Conceptual design Antonio

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

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

West / North end Mi Mirror Mi 2370 Cold surface: length: 2370 mm diameter: 1000 mm Baffles: diameter: 620 mm 3 needed to cover cold surface temperature influences mirror temperature material: glass?

Side view Reinforcement ribs L = 3490 mm D = 1208 mm

Cryo link details Heat bridge/expansion bellows LN2 vessel support LN2 (250 l) superinsulation Baffle D= 620 mm Pumpout Flange (100 mm) 3.2 mm/m

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

Phase separator 2 m above cryo link

Water adsorbtion Layer 1 micron – 5 × H 2 O – Load mbar l/s – Epsilon: 0.1 → 0.2 – 2 years Note the following – Adsorbtion non uniform – Heat load non uniform Emissivity of S.St.

Summary Preliminary design for short cryo links – Length 2.5 m, diameter 1 m – Capacity about 2 years for 1 micron layer – Reduced heat load Lower gas load, less bubbles, less nois Lower LN2 consumption – Effect on mirrors – Reduced cost Test set-up – Operations Closed loop condensor – Bubbles – Etc.