South Korea's KSTAR Achieves New Fusion Plasma Sustenance Records

Key Facts

• KSTAR stands for Korea Superconducting Tokamak Advanced Research.
• Operated by the Korea Institute of Fusion Energy (KFE) in Daejeon, South Korea.
• During the December 2023–February 2024 campaign, KSTAR sustained plasma in high-confinement mode (H-mode) for 102 seconds and ion temperatures of 100 million degrees Celsius for 48 seconds.
• Previous record for maintaining plasma at 100 million degrees Celsius was 30 seconds, set by KSTAR in 2021.
• Upgrades in 2023 included replacement of divertors with tungsten monoblocks, enhancing heat tolerance and divertor performance.
• Tungsten's melting point is 3,422°C, making it suitable for plasma-facing components subjected to intense heat loads.
• KSTAR's ultimate goal is to sustain high-temperature plasma (>100 million °C) for 300 seconds, targeted by 2026.

Background & Context

KSTAR is a superconducting tokamak designed to confine plasma using magnetic fields in a toroidal chamber for controlled nuclear fusion research. Achieving and sustaining plasma at approximately 100 million degrees Celsius is critical, as this temperature enables fusion reactions of deuterium-tritium fuel—an essential step toward generating fusion energy.

High-confinement mode (H-mode), discovered in 1982, is a plasma regime that improves confinement by reducing turbulence at the plasma edge, increasing temperature and density, thereby enhancing fusion reaction performance. Sustaining H-mode plasma for extended durations is vital for realizing steady-state fusion reactors.

Divertors are plasma-facing components that remove heat and impurities from the plasma edge to protect the reactor walls. Tungsten, with its high melting point and durability, replaced earlier carbon-based divertors in KSTAR during 2023 upgrades to allow longer plasma operations with higher heating power.

Why This Matters for Exams / Exam Relevance

These experimental achievements illustrate practical advances toward commercial fusion energy. Exam questions may cover aspects including the functions and importance of tokamaks like KSTAR, specifics of plasma confinement modes (e.g., H-mode), significance of plasma temperature and sustainment durations, as well as material selections such as tungsten for divertors. Understanding KSTAR’s role in the global fusion research landscape and its technological milestones is also crucial.

Points to Remember

• KSTAR is located in Daejeon, South Korea, and operated by the Korea Institute of Fusion Energy.
• The tokamak sustained H-mode plasma for 102 seconds and plasma at 100 million °C for 48 seconds (Dec 2023–Feb 2024), surpassing previous records.
• 2023 upgrades replaced carbon divertors with tungsten monoblocks to improve heat resistance during plasma operations.
• H-mode is an operational plasma regime that enhances confinement by suppressing turbulence at the plasma edge.
• KSTAR aims to sustain plasma exceeding 100 million °C for 300 seconds by 2026—a benchmark for steady-state fusion operation.
• The research supports international projects like ITER and contributes to understanding long-pulse fusion plasma control.