EUROfusion joins ITER tokamak commissioning

On March 13, 2026, Fusion for Energy said European and Japanese teams had begun integrated commissioning of JT-60SA, the tokamak in Naka, Japan that ITER describes as the largest operating machine of its kind. The start of commissioning follows a roughly two-year shutdown after JT-60SA’s initial low-power plasma operations in late 2023, according to Fusion for Energy. EUROfusion and ITER-linked researchers are part of the broader scientific effort around the machine, which Europe and Japan built under their Broader Approach agreement. The work is aimed at testing upgraded systems before a new experimental campaign expected at the end of 2026. ### Which machine is this, exactly? JT-60SA is hosted by Japan’s National Institutes for Quantum Science and Technology, or QST, in the city of Naka. ITER said the machine has a plasma radius of 3 metres and a plasma volume of 130 cubic metres, making it the largest operating tokamak in the world. EUROfusion describes JT-60SA as a joint Japanese-European device that will study plasma operations in preparation for ITER and DEMO, the planned follow-on demonstration reactor. (fusionforenergy.europa.eu) The project sits alongside ITER rather than replacing it. ITER said it has collaboration agreements tied to JT-60SA so it can learn from the machine’s assembly, installation, integrated commissioning and operation. ### Why are EUROfusion and ITER scientists involved on site? EUROfusion has been contributing hardware and personnel to JT-60SA and “will continue to do so,” ITER said when the machine was inaugurated in December 2023. (iter.org) Fusion for Energy said in March that it would follow the commissioning campaign closely with a team stationed in Naka alongside QST. That arrangement puts machine operators, hardware specialists and experiment teams in the same place as systems are brought online. Some 500 researchers from Europe and Japan have been involved in the project, according to ITER. The machine’s next campaign is also drawing interest from the international fusion community, Fusion for Energy said, while outside reporting said more than 150 research proposals were under review from scientists in Europe, Japan and the ITER Organization. Reuters could not independently verify that proposal count from a primary project document. (iter.org) ### What changed during the shutdown? Late 2023 marked JT-60SA’s first plasma, but Fusion for Energy said the machine was switched off shortly afterward for a long upgrade period. During that shutdown, teams installed new components including diagnostics, cryopumps from Europe and additional heating systems intended to support hotter and more powerful plasmas, JT-60SA Project Leader Jerónimo García said. (iter.org) Two 8-metre-diameter ring-shaped in-vessel coils were among the additions. Fusion for Energy said the coils were designed to control plasma position at high speed and were wound directly inside the machine, then connected to European power supplies. The interior was also updated with a new first wall and a divertor using carbon-based armour, the agency said. (fusionforenergy.europa.eu) ### What does “integrated commissioning” mean here? The first stage is a gradual start-up. Fusion for Energy said commissioning begins with systems that can run at room temperature and under non-vacuum conditions, including the in-vessel coils. The next stage is to pump down the cryostat and vacuum vessel to create high-vacuum conditions. (fusionforenergy.europa.eu) After that, teams will cool down and energise the large magnets to validate how the new components work together as one machine, Fusion for Energy said. ### What comes after commissioning? The end of 2026 is the next dated milestone. (fusionforenergy.europa.eu) Fusion for Energy said the commissioning process is expected to lead to a new round of experiments starting at the end of 2026 and running for around six months. QST will host that campaign in Naka, with European and Japanese teams already working through the restart and EUROfusion, Fusion for Energy and ITER-associated researchers using the machine’s operating data to inform later work on ITER and future reactors. (fusionforenergy.europa.eu)