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Major assembly progress on JT-60SA fusion device
Major assembly progress on JT-60SA fusion device
Nine sectors (340 degrees) of the JT-60SA vacuum vessel have been assembled and welded. Eighteen toroidal field coils will now be manoeuvred into place before the vessel is closed up.
The
JT-60SA fusion experiment in Naka, Japan, is designed to support the operation of ITER and to investigate how best to optimize the operation of fusion power plants that are built after ITER.
It is a joint international research and development project involving Japan and Europe, using infrastructure of the existing JT-60 Upgrade experiment. SA stands for "super, advanced," since the experiment will have superconducting coils and study advanced modes of plasma operation. This satellite tokamak program was established in 1997 as one of three joint projects between Europe and Japan within the
Broader Approach Agreement.
Construction has been
underway since January 2013. In the last few months, major assembly milestones have been reported by the European Domestic Agency, including the completion of vacuum vessel assembly and the installation of the machine's cryogenic system.
The vacuum vessel, with a diameter of 10 metres and a height of 6.6 metres, is made of ten sectors that are welded together within strict tolerances of a few millimetres only. Assembly work began in 2013 and was completed recently. Only one sector remains to be welded; before this, 18 toroidal field coils must be manoeuvred into place.
In JT-60SA's cryogenic hall, the large refrigeration cold box (which cools the helium) and the auxiliary cold box (which distributes and controls helium flows) are in place.
Installation of the cryogenic system has also been completed. JT-60SA's cryogenic system, with an equivalent refrigeration capacity of 9 kW at 4.5 K (-269 degrees C), will use helium to cool the superconducting magnets, thermal shields, and cryopumps. Part of the European in-kind contributions to the JT-60SA project, the cryogenic system was a voluntary contribution from France. The European agency collaborated with CEA (the French Alternative Energies and Atomic Energy Commission) to develop the preliminary design and specifications; in November 2013 CEA contracted the detailed design, manufacturing, installation and commissioning of this system to Air Liquide Advanced Technology in Sassenage, France.
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