JT-60SA produces first deuterium plasma at Naka Fusion Institute

Japan's National Institutes for Quantum Science and Technology (QST) and the European EUROfusion consortium jointly announced first deuterium plasma operations on JT-60SA, the world's largest operating superconducting tokamak. The Naka-based device produced a 1.2 MA, 5-second deuterium discharge — the program's first plasma containing fusion-relevant fuel since hydrogen commissioning concluded in 2023.

JT-60SA's mission is to validate advanced tokamak scenarios for ITER and Japan's planned demonstration reactor JA-DEMO, with particular focus on high-beta steady-state operation and negative-ion neutral beam heating. The device uses 22 MW of neutral beam power and 7 MW of electron cyclotron heating; this week's pulse used roughly half of installed heating capacity.

QST president Shirou Kobayashi said the deuterium campaign would run through 2027, after which the machine will be reconfigured for high-performance scenarios. The Naka campus is also home to Japan's IFMIF-DONES fusion materials irradiation facility planning office, giving the country the most complete public fusion infrastructure stack outside of the EU.