Eight sophisticated ‘cold valve boxes’ will regulate the forced flow of supercritical helium to the eight cryopumps of the ITER vacuum system.
Text by Fusion for Energy
European contractors Research Instruments (Germany) and Cryoworld (Netherlands) are manufacturing eight ‘cold valve boxes,’ 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 and the cryostat, 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.
Super critical helium
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. 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 expected before the end of 2022.
About Fusion for Energy
Fusion for Energy (F4E) is the European Union organisation managing Europe’s contribution to ITER— the biggest scientific experiment on the path to fusion energy. This partnership of seven parties (China, Europe, Japan, India, the Republic of Korea, the Russian Federation and the USA), represents half of the world’s population and 80% of the global GDP. Europe is responsible for nearly half of the project, while the other six parties contribute equally to the rest.
