Completion of the Fast Plasma Positioning Control Coil for stable confinement of the world’s largest plasma

Fabrication of an 8-meter coil inside the JT-60SA vessel with ±2 mm accuracy

[News Highlights]

• Two Fast Plasma Positioning Control Coils (FPPCs) for maintaining stable plasma during the plasma heating experiments scheduled to begin in 2026, have been completed for JT-60SA—the world’s largest superconducting tokamak— jointly constructed by Japan and Europe in Naka City, Ibaraki Prefecture.
• The FPPC is an 8-meter-diameter copper coil, installed inside the JT‑60SA vacuum vessel (inner diameter 10 meters). During fabrication, engineers successfully overcame the technical challenge of winding coil within the confined environment of vacuum vessel, achieving positional and shape accuracy within ±2 millimeters.
• The technology developed with JT-60SA contributes to the fabrication of in-vessel coils for ITER, currently under construction in southern France. Going forward, the advanced technology for stable control of the world’s largest plasma using the FPPC at JT‑60SA will serve as an important foundation for advancing plasma control technologies amid intensifying international competition, and for establishing the autonomy and high reliability of DEMO reactors.