JT-60 (short for Japan Torus-60) is a large research tokamak, the flagship of the Japanese National Institute for Quantum Science and Technology's fusion energy directorate.
[2][3] SA stands for super advanced tokamak, including a D-shaped plasma cross-section, superconducting coils, and active feedback control.
In February 1997, a modification to the divertor from an open-type shape to a semi-closed W-shape for greater particle and impurity control was started and later completed in May.
[11][12][13] Experiments simulating the helium exhaust in ITER were promptly performed with the modified divertor, with great success.
In 1998, the modification allowed JT-60U to reach an extrapolated fusion energy gain factor of QDTeq = 1.25 at 2.6 MA.
[17] In fiscal year 2003, the plasma discharge duration of JT-60U was successfully extended from 15 s to 65 s.[18] In 2005, ferritic steel (ferromagnet) tiles were installed in the vacuum vessel to correct the magnetic field structure and hence reduce the loss of fast ions.
[19][20] The JAEA used new parts in the JT-60, having improved its capability to hold the plasma in its powerful toroidal magnetic field.
It is a fully superconducting tokamak with flexible components that can be adjusted to find optimized plasma configurations and address key physics issues.
After a major short circuit during integrated commissioning in March 2021 necessitating lengthy repairs, it was declared active on December 1, 2023.
[29] In January 1996, a paper detailing the superconducting properties of Nb3Al composite wire and its fabrication process was published in the 16th International Cryogenic Engineering/Materials Conference journal.
[31] Designs and intentions for the modification varied over the next decade, until February 2007, when the Broader Approach Agreement was signed between Japan and the European Atomic Energy Community.
[32] In it, the Satellite Tokamak Program established a clear, defined goal for JT-60SA: act as a small-scale ITER.
[33]: 3.3.1 Construction of the tokamak officially began on 28 January 2013 with the assembly of the cryostat base, which was shipped from Avilés, Spain over a 75-day long journey.
[a] The event was highly publicized through local and national news, and reporters from 10 media organizations were able to witness it in person.