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The Korean artificial sun KSTAR sets a new world record of 20-second-long operation at 100 million degrees


Date of registration 2021-01-25

Aiming to operate continuously high-temperature plasma over 100 million degrees for 300 seconds by 2025


temperature plasma for 20 seconds with an ion temperature exceeding 100 million degrees.


On November 24, the KSTAR Research Center at KFE announced that in joint research with Seoul National University (SNU) and Columbia University in the United States, it succeeded in the continuous operation of plasma for 20 seconds with an ion temperature higher than 100 million degrees, which is one of the core conditions of nuclear fusion in the 2020 KSTAR Plasma Campaign.


It is an achievement to extend the eight-second plasma operation time during the 2019 KSTAR Plasma Campaign by more than two times. In its 2018 experiment, KSTAR reached a plasma ion temperature of 100 million degrees for the first time (retention time: about 1.5 seconds).


Recreating the fusion reactions of the sun, given its ultra-high temperature and density, on earth requires heating and the maintenance of ion temperatures exceeding 100 million degrees after fueling a fusion device such as KSTAR and dividing nuclei into ions and electrons to create a plasma state. 


Thus far, there have been other fusion devices that have briefly managed plasma at temperatures of 100 million degrees or higher. None of them broke the barrier of maintaining the operation for ten seconds or longer. This represented the operational limit of a normal conducting device,* and it was difficult to maintain a stable plasma state in the fusion device at such a high temperature for a long time.

* Limits of a normal conduction device: Unlike KSTAR, a fusion device that features a superconducting magnet, existing fusion devices based on normal conducting magnets such as copper magnets cannot be operated for an extended period of time because when a high electric current runs through the magnet to create a magnetic field that is strong enough to confine plasma, the magnet overheats due to its resistance.


In its 2020 experiment, KSTAR improved the performance of the internal transport barrier (ITB) mode, one of the next-generation plasma operation modes developed in 2019 and succeeded in maintaining the plasma state for a long period of time, overcoming the existing limits of the ultra-high-temperature plasma operation.


Director Si-Woo Yoon of the KSTAR Research Center at the KFE explained, “The technologies required for long operations of 100 million-degree plasma are the key to the realization of fusion energy, and KSTAR’s success in maintaining high-temperature plasma for 20 seconds will be an important turning point in the race for securing the necessary technologies for long high-performance plasma operation, a critical component of a commercial nuclear fusion reactor in the future.”


“The success of the KSTAR experiment in the long high-temperature operation by overcoming certain drawbacks of the ITB modes brings us a step closer to the development of technologies leading to the realization of nuclear fusion energy,” added Yong-Su Na, a professor in the Department of Nuclear Engineering at SNU, who has been jointly conducting research on the KSTAR plasma operation.


KSTAR is going to share its key experiment outcomes in 2020, including this success, with fusion researchers around the world at the IAEA Fusion Energy Conference to be held in May of 2021.


The final goal of KSTAR is to succeed in continuous operation of 300 seconds with an ion temperature higher than 100 million degrees by 2025.

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