South Korea’s ‘artificial sun’ KSTAR sets new world record in plasma operation

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Scientists at South Korea’s magnetic fusion device Korea Superconducting Tokamak Advanced Research (KSTAR) announced late last month that KSTAR had set a world record by reaching the temperature of over 100 million degrees Celsius for a period of 48 seconds. 

The previous such record achieved by KSTAR was in 2021 when it reached the ion temperature of over 100 million degrees Celsius for a period of 20 seconds. 

Following the latest record, the Director of the KSTAR Research Center at the Korean Institute of Fusion Energy, Si-Woo Yoon, told media persons that high temperature and high-density plasmas, in which reactions can occur for long durations, are vital for the future of nuclear fusion reactors.  

“Sustaining these high temperatures has not been easy to demonstrate due to the unstable nature of the high temperature plasma,” Si-Woo Yoon said.  

In comparative terms, KSTAR was able to attain 6.6 times the temperature of the Sun, which radiates at a temperature of only 15 million degrees Celsius. 

Referred to as South Korea’s “artificial Sun”, KSTAR had achieved a similar feat also in 2018, but the temperature then could only be maintained for one and a half seconds. In 2019, the device repeated its performance and retained the temperature for a period of 8 seconds, setting a record thereby, and increasing the duration over its previous plasma operation by more than two times.  

It has earlier proved difficult to maintain a stable plasma state in the fusion device at such high temperatures for a long time. In its 2021 experiment, the KSTAR managed to improve the performance of its Internal Transport Barrier (ITB) and succeeded in maintaining the plasma state for a longer period, overcoming the existing limits of the ultra-high temperature plasma operation. 

The KSTAR has a target to increase the plasma operation performance to 300 seconds by the year 2026. 

According to Si-Woo Yoon, KSTAR’s work will be of great help to secure the predicted performance in the International Thermonuclear Experimental Reactor (ITER) operation in time and to advance the commercialisation of fusion energy. 

The world’s largest science project involving 35 countries, the ITER machine, currently being assembled at Cadarache in France, expects to generate the first ultra-hot plasma in late 2025.  It is intended to demonstrate that fusion power can be generated on a commercial scale. 

ITER will be the first project to achieve self-heating plasma and is expected to generate 10 times more heat than is put in.  

Fusion provides clean, reliable energy without carbon emissions, with minute amounts of fuel and no physical possibility of an accident with meltdown. The fuel for fusion is found in seawater and lithium, while it is abundant enough to supply the world for millions of years. A football-sized amount of this fuel is equivalent to around 10,000 tons of coal. 

The plant at ITER will produce about 500 MW of thermal power. If operated continuously and connected to the electric grid, that would translate to around 200 MW of electric power, which is sufficient for the average needs of 200,000 homes. A commercial fusion plant will be designed with a slightly larger plasma chamber, for 10-15 times more electrical power. For instance, a 2,000 MW fusion power plant could supply electricity to two million homes. 

Tokamak (derived from the Russian words for “toroidal magnetic confinement”) devices, originally developed in Russia, are used to recreate fusion reactions that occur in the Sun. According to the Institute for Radiation Protection and Nuclear Safety, there are about 250 tokamak devices around the world. 

In 2021, the China National Nuclear Corporation announced it had switched on its “artificial Sun”, which managed to operate at 150 million degrees Celsius. In November 2018, the Institute of Plasma Physics in Hefei, China, had announced that an Experimental Advanced Superconducting Tokamak device had reached a milestone temperature of 100 million degrees Celsius and heating power of 100 MW.