Korean nuclear fusion reactor sets new record

The Korea Superconducting Tokamak Advanced Research (KSTAR) is a cutting-edge project in nuclear fusion research. A few days ago, the structure stood out again by setting new records in terms of sustained fusion temperature and plasma confinement duration.

The principle of fusion

Nuclear fusion is the process by which the nuclei of two light atoms, such as hydrogen, fuse to form a heavier nucleus , releasing a considerable amount of energy along the way. This process is at the heart of how stars, including our Sun, work. Inside stars, where temperatures and pressures are extremely high, hydrogen atoms are subjected to such powerful forces that they eventually fuse to form helium . This process releases a huge amount of energy in the form of light and heat, which allows the star to shine and provide heat to its surroundings.

On Earth, recreating these extreme conditions for nuclear fusion is a major technical challenge. The temperatures necessary to initiate fusion are indeed incredibly high, on the order of hundreds of millions of degrees Celsius. At such temperatures, atoms move at extremely high speeds, allowing them to overcome electrical repulsions and fuse.

In fusion reactors, magnetic fields keep a plasma, which is an ionized gas made up of nuclei and free electrons, confined to a restricted area. When conditions are right, hydrogen nuclei in the plasma fuse to form helium, releasing energy. This energy can then be harvested and converted into electricity, providing a clean and virtually unlimited source of energy.

Korean Artificial Sun breaks record

The Korea Superconducting Tokamak Advanced Research (KSTAR), also known as the Korean Artificial Sun, is one such reactor. Over the years, KSTAR has gradually improved its performance in controlled nuclear fusion. In 2018, the team managed to reach a temperature of 100 million degrees Celsius for the first time, but only for 1.5 seconds . A year later, this duration was extended to 8 seconds , then to 20 seconds in 2020. In 2021, a new record was set when the plasma was maintained at this temperature for half a minute .

Since then, the Korea Institute of Fusion Energy (KFE) team has undertaken significant improvements to the device. Notably, she constructed a new tungsten diversion environment, which increased the length of time plasma can be maintained at a temperature of 100 million degrees Celsius. Now , KSTAR can withstand this temperature for 48 seconds .

A high containment mode

KSTAR would also be able to hold hot plasma in high confinement mode (H mode) for 102 seconds . In detail, when we talk about maintaining a temperature of 100 million degrees Celsius for 48 seconds, this means that the reactor managed to reach this extremely high temperature and maintain it for this specific duration. This measures the reactor's ability to heat plasma to a nuclear fusion temperature for a given amount of time.

In contrast, keeping the plasma hot in high confinement mode (H mode) for 102 seconds refers to the reactor's ability to maintain the plasma at a high temperature while maintaining optimal magnetic confinement conditions. H mode is a specific operating mode in which the reactor manages to maintain more stable and prolonged fusion performance. Thus, this not only shows the ability to heat the plasma, but also to keep it stable and hot in a particular operating mode . The Korean team's ultimate goal would be to extend this duration further and reach 300 seconds of plasma burning by the end of 2026 .

Beyond its individual achievements, KSTAR is an integral part of global nuclear fusion research. Projects like the Joint European Torus (JET) complement the efforts made to understand and master this promising technology. These experimental reactors serve as test beds for large-scale prototypes such as ITER. The latter, designed to generate ten times more energy than that consumed, will come into service in a few years.