Cold valve boxes for the ITER cryopumps
Eight sophisticated "cold valve boxes" will regulate the forced flow of supercritical helium to the eight cryopumps of the ITER vacuum system. European contractors Research Instruments (Germany) and Cryoworld (Netherlands) are manufacturing these high-tech cryogenic components that are built to withstand the hostile environment near the plasma.
After mechanical pumps perform the initial pump-down of the ITER vacuum vessel and cryostat, powerful cryopumps will take over to attract any remaining molecules to the ultra-cold surface of their cryopanels. Eight cryopumps are planned to exhaust the vacuum vessel (6) and the cryostat (2), each one equipped with numerous "cryopanels" that will be cooled down to 4.5 K (minus 268.5 °C) by a flow of supercritical helium.
At Research Instruments, the four-tonne cold valve boxes will be equipped with final electrical wiring and pneumatic connections before undergoing factory acceptance testing. © RI, August 2022
Regulating this flow of supercritical helium are the cold valve boxes associated with each pump. Equipped with cryogenic valves (25 per unit), relief systems, and sensors for pressure and temperature, these components will manage cryogenic fluids in a wide range of temperatures—from super-cold (-269 °C) to fairly hot (230 °C).
High magnetic field, radiation, and space were part of the design constraints. The position of the cold valve boxes in the machine imposed special constraints on materials and welding, while regular "regeneration periods" for each pump complicated their design.
Based on a contract for the final design and fabrication of the cold valve boxes awarded by the European Domestic Agency Fusion for Energy in 2018, Research Instruments (already involved in the manufacture of the ITER cryopumps) contracted with Cryoworld BV for the torus and cryostat cold valve boxes.
Two cold valve boxes are ready for transportation from Cryoworld to Research Instruments, © RI, July 2022
Cryoworld has already shipped four of eight units to Research Instruments, where final electrical wiring and connections will be installed, and factory acceptance testing carried out. Delivery to ITER is expected before the end of the year.
See the original story on the Fusion for Energy website.
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