The JT-60SA tokamak, the world's largest operational experimental fusion device, was inaugurated on December 1 in Naka, Japan. This event follows the successful achievement of the machine's first plasma on October 26, 2023, marking a critical step in its commissioning phase. The project is a joint venture between Japan's National Institutes for Quantum Science and Technology (QST) and the European Union's agency, Fusion for Energy. As a satellite experiment for the ITER program, JT-60SA is designed to investigate advanced operational scenarios and provide crucial data to optimize the performance of the larger ITER device currently under construction in France. The six-story-tall machine will not produce net energy but will serve as a key risk-mitigation and research platform. Source: ITER

JT-60SA's primary mission is to sustain high-temperature plasma for extended durations, with a target of approximately 100 seconds. This is a significant pulse length for a device of this scale and is essential for studying plasma-wall interactions, heat exhaust, and control strategies relevant to future fusion power plants. The operational goal is to heat a deuterium plasma to a temperature of 200 million degrees Celsius. While it is a precursor to deuterium-tritium (D-T) operations at ITER, JT-60SA itself will focus on deuterium experiments, providing a non-nuclear environment to test key physics and engineering systems. Its findings will directly inform the operational plans for ITER's initial non-tritium phases. Source: ITER

JT-60SA's primary mission is to sustain high-temperature plasma for extended durations, with a target of approximately 100 seconds.

The project represents a substantial international collaboration, with construction beginning in 2007 and assembly completing in 2020. The European Union's contribution is valued at approximately 500 million euros, covering components and support systems procured through Fusion for Energy. This collaboration allows for shared expertise and resource pooling, accelerating the development timeline for fusion energy. The device's advanced superconducting magnet system and divertor are designed to handle high heat and particle fluxes, making it a unique testbed for technologies that must perform reliably in the demanding environment of a burning plasma machine like ITER. This international effort in public-sector fusion research complements the diverse approaches being pursued in the private sector. Source: ITER

While JT-60SA is now the largest operational tokamak, it is distinct in purpose from other major fusion experiments. Unlike the National Ignition Facility in the US, which uses inertial confinement fusion and has achieved scientific energy breakeven (Q > 1), JT-60SA uses magnetic confinement. Its scale and mission are also different from ITER, which is significantly larger and is designed to be the first device to produce a net energy gain (Q > 10) from a sustained D-T burning plasma. JT-60SA's role is to bridge the gap, providing operational experience and physics data at a reactor-relevant scale to ensure ITER can achieve its ultimate goals efficiently and safely. The results will be cataloged alongside other major confinement achievements in the global fusion database. Source: ITER

With commissioning underway, the next phases for JT-60SA will involve systematically increasing plasma current, heating power, and pulse duration to reach its design parameters. Researchers will focus on validating plasma control schemes, testing the performance of the divertor under high thermal loads, and exploring advanced tokamak operating modes like the high-confinement H-mode. The data generated over the coming years will be openly shared between the Japanese and European fusion communities, providing a critical knowledge base for the first operational campaigns at ITER. The successful operation of JT-60SA is therefore a key dependency for the broader international fusion roadmap. Source: ITER