The most advanced cryogenic technologies will be deployed to generate the extremely low temperatures needed for the ITER magnets, thermal shields and cryopumps. The magnets will be cooled with super critical helium to reach a superconducting state at 4.5 K, close to absolute zero, to confine the hot plasma which is expected to reach 150 million ˚ C.
Europe has entrusted Air Liquide to provide the Liquid Nitrogen (LN2) Plant and the auxiliary systems that will cool down, process, store, transfer and recover the cryogenic fluids of the machine. Two nitrogen refrigerators will be manufactured plus two 80 K helium loop boxes, warm and cold helium storage tanks, dryers, heaters and the helium purification system.
In summer we reported on the successful factory acceptance testing of the first two heat exchangers for the 80 K loop boxes, manufactured in Amagasaki, Japan by Sumitomo Precision Products. Since then, further advancements have taken place marking another milestone for F4E, ITER International Organization and their suppliers contributing to the cryogenic system of the biggest fusion device.
At Heatric, UK, two additional heat exchangers have successfully passed a global helium leak test consisting of liquid nitrogen cold tests and a helium leak test to check the compliance of the equipment. In a nutshell, the heat exchangers were exposed to a thermal shock with temperatures ranging from to 23 ˚ C to -196 ˚ C and passed all technical hurdles and inspections without any problems.
The heat exchangers are “key components” for the refrigeration of the cryogenic system. Basically, they exchange heat between two circuits: one with helium gas and another with liquid nitrogen. They have been designed and produced meeting the highest quality requirements. The Heatric units are manufactured by a unique process known as 'diffusion bonding', a process that creates an exchanger core with no joints, welds or points of failure.
Having concluded the tests successfully, the equipment will be packed and delivered to China. There they will join the two heat exchangers manufactured in Japan and will be integrated in the cold box that will be manufactured.