Korea’s ‘artificial sun’ achieves a record 48 seconds at 100 million degrees. Why does it matter?

KSTAR Vacuum vessel
KSTAR Vacuum vessel Copyright Korea Institute of Fusion Energy (KFE)
Copyright Korea Institute of Fusion Energy (KFE)
By Oceane Duboust
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Korea’s ‘artificial sun’, KSTAR, recorded a plasma operation with a temperature of 100 million degrees Celsius for 48 seconds, a new step in nuclear fusion research.


Korea’s “artificial sun” broke its own record during a plasma operation in which temperatures of 100 million degrees Celsius were supported for 48 seconds, a promising new step toward nuclear fusion.

The Korea Superconducting Tokamak Advanced Research or KSTAR had previously set a record of reaching 100 million degree plasma for 30 seconds in 2021, the Korea Institute of Fusion Energy (KFE) said in a statement.

Nuclear fusion happens when two light atoms’ nuclei merge to form a single heavier one, generating a huge release of energy.

This phenomenon powers stars, including the sun, which is why KSTAR has been nicknamed an “artificial sun”.

For stars, this process happens due to a massive gravitational force which creates a crushing pressure in the core keeping the nuclei close enough for fusion to occur.

However, achieving fusion on Earth is extremely challenging. It requires recreating the extreme conditions of temperature and pressure found in stars.

Several installations are investigating the possibility of achieving it such as KSTAR.

KSTAR serves as a pilot for the France-based International Thermonuclear Experimental Reactor (ITER) which Euronews Next visited last year. The “artificial sun” provides information that will help better understand fusion.

KSTAR is a superconducting tokamak, which is a doughnut-shaped machine that uses powerful magnets to trap gas in extreme heat in a state of matter called plasma.

Goal of 300 seconds by 2026

“This research is a green light for acquiring core technologies required for the fusion DEMO reactor,” Dr Suk Jae Yoo, president of the Korea Institute of Fusion Energy (KFE), said in a statement, referring to the experimental nuclear fusion reactors that aim to demonstrate the production of electricity from nuclear fusion, basically ITER’s successor.

“We will do our best to secure core technologies essential for the operation of ITER and the construction of future DEMO reactors”.

Currently, the goal of KSTAR is to improve performance to achieve the goal of “300 seconds of plasma operation with ion temperatures over 100 million degrees,” according to KFE.

Already, 100 degrees Celsius is more than six times the temperature of the sun’s core.

Extending the duration for which KSTAR can maintain extreme temperatures is crucial for achieving a "steady-state" fusion reaction, which is why the record is so important.

In 2023, a part of the tokamak called divertors was upgraded using tungsten. Used to extract heat and ash produced by the fusion reaction protecting the surrounding walls, the new divertors showed only a 25 per cent increase in surface temperature under similar heat loads.

“Despite being the first experiment run in the environment of the new tungsten divertors, thorough hardware testing and campaign preparation enabled us to achieve results surpassing those of previous KSTAR records in a short period,” Dr Si-Woo Yoon, Director of the KSTAR Research Centre.

Additionally, these experiments confirmed the functionality and reliability of KSTAR's core systems, including heating, diagnostics, and controls.

“To achieve the ultimate goal of KSTAR operation, we plan to sequentially enhance the performance of heating and current drive devices and also secure the core technologies required for long-pulse high-performance plasma operations,” he added.

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