Cryoplant
The cryoplant supplies supercritical or gaseous helium to superconducting magnets and cold structures, current leads, feeders, cryopumps, and the thermal shields.
Refrigerator capacity is ~9 kW at 4.5K for a demand estimated at ~8kW. The plant has four main parts:
- a helium refrigerator, composed of a set of warm screw compressors, oil/water removal system, pressure control and gas management, refrigerator coldbox, and a local control system - the coldbox supplies 80K helium gas for thermal shields, 50K helium gas for high temperature superconductor current leads, supercritical helium (4.4K) for the magnet system, and liquid helium at 3.7K for the divertor cryopumps;
- an auxiliary cold box to distribute and control helium flow, and including a buffere and circulation pumps to handle the pulsed loads;
- a gas storage and distribution system composed of warm helium storage, liquid nitrogen storage, cryogenic transfer lines, and warm interconnecting pipework;
- auxiliary equipment such as pneumatic and vacuum systems for the different cold boxes and cryolines.
A new compressor building is being built in the west side vacant area of the JT-60 experimental building to limit the inoise from the compressors. The cryogenic hall neighbouring the JT-60SA torus hall is being refurbished to accommodate the remaining cryogenic system and a dedicated area is being prepared for gas storage.