Korea institute of Fusion Energy (KFE) said on the 27th that it has begun its 2025 experiment with the Korea Superconducting Tokamak Advanced Research (KSTAR) device, aiming to secure plasma operation technology needed to run future fusion reactors. Plasma refers to a state, like in the sun, in which matter at ultra-high temperature and ultra-high pressure separates into atomic nuclei and electrons.
Fusion mimics the principle by which the sun produces energy. In the sun, light atoms such as hydrogen fuse in a plasma state and transform into heavier helium nuclei. In this process, an enormous amount of energy is released in proportion to the mass that is reduced.
To realize fusion energy, it is essential to secure operation technology that can stably maintain ultra-high-temperature plasma for a long time. KSTAR has achieved world-class results in the field of long-duration operation of high-performance plasma and has recently been pushing forward experiments in earnest to prepare for operating future fusion reactors.
As part of that effort, in 2023 it replaced the divertor with tungsten material, which will be used as the inner wall material of the International Thermonuclear Experimental Reactor (ITER) and future fusion reactors, and has continued research to strengthen plasma operation capabilities in a tungsten environment. A divertor is a device that removes heat before it reaches the vacuum vessel and eliminates remaining impurities.
Past experiments focused on adapting to this environment and reproducing existing high-performance plasma operation results, but starting with this year's experiment, based on that work, the plan is to concentrate on developing high-performance plasma operation scenarios that can stably operate plasma even in a tungsten environment.
Tungsten has the advantage of being highly resistant to high temperatures, but it also has the drawback that generated impurities degrade plasma performance. For this reason, controlling tungsten impurities is considered one of the most important challenges in the international fusion research community.
To solve this problem, KSTAR plans to apply various control methods, such as heating and fuel injection, under multiple operating conditions, precisely analyze impurity behavior, and study effective suppression measures in depth.
In addition, to realize plasma that meets all the requirements for future fusion reactor operation—high pressure, sustained current, and stability—the interactions among key operating elements such as heating, current drive, and magnetic field control will be comprehensively verified.
In particular, real-time control technology using artificial intelligence (AI) and Machine Learning will be applied to quickly detect and respond to changes in plasma, and research will also be conducted in parallel to identify physical phenomena, such as fast ions, that may occur during future fusion reactor operation.
Director Oh Young-guk said, "As efforts to accelerate the commercialization of fusion energy are becoming active around the world, KSTAR is also speeding up the acquisition of technologies that will be directly used in operating future fusion reactors," and added, "Through international joint research and the application of the latest technologies such as AI in this experiment, we will further strengthen our capabilities for realizing fusion energy."
Meanwhile, this KSTAR plasma experiment will run through December, and after about a month of maintenance, the 2026 plasma experiment will begin immediately in Feb. next year.
It is unusual to carry out two years of experiments consecutively without suspending device operations, and this is a measure to push forward the work to replace the entire inner wall of KSTAR with tungsten tiles following the installation of a tungsten divertor in 2023.