South Korea’s superconducting tokamak, engineered for long-pulse high-performance plasma research and a world leader in sustained high-temperature confinement.
KSTAR (Korea Superconducting Tokamak Advanced Research) is a fully superconducting tokamak operated by the Korea Institute of Fusion Energy (KFE, formerly the National Fusion Research Institute) in Daejeon, South Korea. When it achieved first plasma in June 2008, KSTAR became the first tokamak in the world to employ Nb3Sn superconducting magnets for its toroidal-field coils—the same advanced superconductor technology later adopted for ITER’s central solenoid and toroidal-field magnets. This engineering achievement was a verified milestone in magnet technology for fusion.[1]
KSTAR’s 16 toroidal-field coils use Nb3Sn cable-in-conduit superconductors, while its poloidal-field coils use NbTi—mirroring the magnet-material choices later implemented at ITER. The coils operate at approximately 4.5 K, cooled by a helium refrigeration system. The machine is designed for D-shaped plasmas with strong shaping (elongation ~2, triangularity ~0.8) in a single-null divertor configuration. The vacuum vessel and in-vessel components have been progressively upgraded, including the installation of tungsten divertor tiles in recent campaigns.[1]
The heating and current-drive systems include neutral beam injection, electron cyclotron resonance heating at 110 GHz and 170 GHz, and ion cyclotron heating. An advanced real-time plasma control system, developed in collaboration with U.S. and European partners, enables precise shape and profile control during long-pulse operations.[2]
KSTAR has become internationally recognized for sustained high-temperature plasma operation. In a series of campaigns from 2018 onward, the KSTAR team progressively extended the duration of H-mode plasmas at ion temperatures exceeding 100 million °C (approximately 8.6 keV). In 2021, KSTAR reported maintaining these conditions for 30 seconds, and in 2024 the team reported extending this to 48 seconds. These durations, while widely reported, are claimed records; the full peer-reviewed analysis should be consulted for precise diagnostic conditions and definitions.[3]
KSTAR has also contributed verified results in the areas of ELM control using resonant magnetic perturbations (in collaboration with DIII-D researchers), fast-ion confinement studies, and the development of disruption avoidance and mitigation strategies. Its advanced ECE imaging diagnostic provides uniquely detailed 2D measurements of electron temperature fluctuations.[2]
As of 2026, KSTAR continues active experimental campaigns with a research program focused on extending high-performance pulse duration, developing ITER-relevant operating scenarios, and testing tungsten divertor components. South Korea’s national fusion strategy positions KSTAR as the core experimental facility for building the physics and technology basis for K-DEMO, a proposed Korean demonstration fusion power plant. KFE has outlined plans for further heating system upgrades to increase the accessible plasma performance.[2]