1. Heinz Grote1 Presentation to NSCX WENDELSTEIN 7-X Assembly Max-Planck- Institut für Plasmaphysik KKS-Nr.: 1-AD Dok-Kennz.: -Txxxx.0 Heinz Grote October 2007 Vacuum Systems at Wendelstein 7-X and Leak Testing during Assembly Insulating vacuum in the cryostat Ultra-high-vacuum in the plasma vessel Interspace Vacuum system for multilayer bellows, double sealings, control coils, el. feedthroughs Evacuation of the gas inlet into the plasma vessel – already working Insulating vacuum in cryostats of the gyrotrons ECRH – already working Vacuum system for pellet injection Vacuum system and gas inlet NBI Insulating vacuum ICRH Vacuum systems for diagnostics (many) Vacuum system for the cooling machine...

2. Heinz Grote2 Max-Planck-Institut für Plasmaphysik, EURATOM Association Leak testing Strategy All components to be assembled are leak tested with Helium or SF 6 -before delivery (qualification of the workshops varies) -during incoming inspection -after re-work -on the assembly stands immediately after welding or mounting of the sealings -finally in an integral leak test after closing the cryostat and the plasma vessel Where ever possible pressure gradients during testing are equal as in working condition Where ever possible tubes and weldings of cryogenic parts are tested at temperature of LN 2

3. Heinz Grote3 Max-Planck-Institut für Plasmaphysik, EURATOM Association Leak testing Equipment (1) All large components are leak tested with Helium in a vacuum tank Volume: 55 m³ inner diameter: 4.900 mm max. inner height : 3.150 mm max. height of load (crane height): 2.600 mm max. weight of load: 7.500 kg base pressure (< 2*10-7 mbar empty tank) (< 3*10-5 mbar loaded with W7-X coil) double–O–ring seal [Viton] with interspace pumping 26 CF-ports various size pumps: 4 x 65m³/h rotary vane pumps, 2 x 1.000m³/h roots-pumps 2 x cold traps 2 x 1.000 l/s turbomolecular pumps, used for W7-X coil Paschen tests, He-leak tests of superconductors and He-cooling tubes on coils, support structure etc.

4. Heinz Grote4 Max-Planck-Institut für Plasmaphysik, EURATOM Association Leak testing Equipment (2) All joints and weldings are leak tested locally with special designed chambers or flexible bags Variety of silicone sealed leak detection chambers made of stainless steel

5. Heinz Grote5 Max-Planck-Institut für Plasmaphysik, EURATOM Association Leak testing Equipment (3) Leak detection chamber made of Al sealed with Tacky Tape

6. Heinz Grote6 Max-Planck-Institut für Plasmaphysik, EURATOM Association Leak testing Equipment (4) Leak detection chamber made of stainless steel foil sealed with Tacky Tape

7. Heinz Grote7 Max-Planck-Institut für Plasmaphysik, EURATOM Association Leak testing Equipment (5) Silicone sealed stainless steel chamber for assuring 100 % He-atmosphere during leak testing Temperature sensor He- service pipe Data logger Leak testing at 77 K

8. Heinz Grote8 Max-Planck-Institut für Plasmaphysik, EURATOM Association Mechanical Pumping System - Cryostat Requirements during pump down Requirements during pump down from atmospheric pressure Evacuation down to 1 mbar 24 hours Evacuation down to 1 * 10 -2 mbar72 hours (from 1 down to 1 * 10 -2 mbar in 48 hours) Cooling down p < 1 * 10 -2 mbar Outgassing rate of the insulation 1 * 10 -5 mbar * l/(s * m²) Load of the insulation with water vapor0.25 g/m² Amount of the insulation30 layers á 1,400 m² (conservative assumption)

9. Heinz Grote9 Max-Planck-Institut für Plasmaphysik, EURATOM Association Mechanical Pumping System - Cryostat Working requirements, Geometry Working Requirements Max. partial pressure (He)1 * 10 -5 mbar Max. tolerable leak (He)1 * 10 -2 mbar*l/s S eff >= 1,000 l/s (inside the cryostat) 1,000 l/s in the cryostat 2,000 l/s at the port 3,180 l/s Geometry Ports for pumping 3 per module (= 15 overall), diameter 500 mm each Volumeapprox. 500 m³

10. Heinz Grote10 Max-Planck-Institut für Plasmaphysik, EURATOM Association Mechanical Pumping System - Cryostat Layout Pumping set on each of the 5 modules Gate valve DN 320 ISO F Tube DN 320, length 4 m Bypass DN 100 TMP 2,000 l/s Rotary vane pump 65 m³/h Roots pump 250 m³/h) ) on 2 modules only Rotary vane pump 65 m³/h)

11. Heinz Grote11 Max-Planck-Institut für Plasmaphysik, EURATOM Association Mechanical Pumping System - Cryostat Present status Uwe Schultz

12. Heinz Grote12 Max-Planck-Institut für Plasmaphysik, EURATOM Association Pumping System for Plasma Vessel - Base pressure, UHV-conditions, 10 -8 mbar Turbomolecular pumps (TMP) - Experimental, 10 -5 - 10 -4 mbar Hydrogen (Deuterium, Helium) up to 10 -3 mbar in the Divertor high gas load Cryopumps, TMP + Roots + Rotary-pumps (3-stage mechanical pump system) - Regeneration of Cryopumps with TMP - Pumping through divertor gap:Cryopumps behind the target modules TMP: 10 individual systems 1 in each divertor unit at the ports AEH and AEP

13. Heinz Grote13 Max-Planck-Institut für Plasmaphysik, EURATOM Association Pumping System for Plasma Vessel Requirements for the Pumping System Experiment: 3*10 21 s -1 1.5*10 21 molecules*s -1 ~ 50 mbar*l/s Pressure in Divertor: 100*10 3 l/s cryo pumps: 75*10 3 l/s for H 2 TMP: 25*10 3 l/s for H 2 Pump down: ca. 1,300 m² inner surface, (1,000 m² stainless steel, 300 m² carbon, B 4 C) outgassing: 1*10 -7 mbar*l/(s*m²) (SS), 1*10 -6 mbar*l/(s*m²) (C, B 4 C), total: 4*10 -4 mbar*l/s base pressure : 40*10 3 l/s TMP only

14. Heinz Grote14 Max-Planck-Institut für Plasmaphysik, EURATOM Association Pumping System for Plasma Vessel Mechanical pumping system – Layout of 1 unit Pumping gap  2,430 l/s  2,870 l/s node:  3,200 l/s 2*1,850 l/s = 3,700 l/s Pumping gap  1,340 l/s  1,460 l/s 1,850 l/s Port AEH Port AEP Total approx.: 37.7*10³ l/s  25*10³ l/s at the ports AEH alone necessary for operation in the standard case, where the interaction zone of the plasma with the divertor targets is located near this port

15. Heinz Grote15 Max-Planck-Institut für Plasmaphysik, EURATOM Association Pumping System for Plasma Vessel Location of the Ports Pumping ports AEP AEH

16. Heinz Grote16 Max-Planck-Institut für Plasmaphysik, EURATOM Association Pumping System for Interspace Vacuum Present status 38 rectangular and oval ports with multilayer bellows (Plasma Vessel) 1 – 100 mbar to be vented only if both the cryostat and the plasma vessel are vented 40 rectangular and oval ports with double sealings (Plasma Vessel) ~ 0.1 – 1 mbar to be vented together with the plasma vessel 146 cryostat ports with double sealings ~ 0.1 – 1 mbar to be vented together with the cryostat 3 independent roughing vacuum systems – fivefold each according to W7-X modules (dry roughing pump, valve, measuring gauge, tubes to ports DN12-20) 10 control coils will have interspace vacuum to protect the plasma vessel from water leaks 14 electrical feedthroughs – not permanently pumped

17. Heinz Grote17 Max-Planck-Institut für Plasmaphysik, EURATOM Association Control Schematic for Pumping System W7-X based on SIMATIC S7-400 master programmable logic controllers part components W7-X Olaf Volzke central main control W7-X