Video: Nuclear experiment in one of the most powerful machines in the world 1:27

(CNN) --

South Korean scientists announced a new world record for the time they maintained temperatures of 100 million degrees Celsius (seven times hotter than the Sun's core) during a nuclear fusion experiment, in what they say is an important step forward for that futuristic energy technology.

Nuclear fusion seeks to replicate the reaction that makes the Sun and other stars shine, fusing two atoms to release enormous amounts of energy. Often referred to as the holy grail of climate solutions (clean energy), fusion has the potential to provide unlimited energy without planet-warming carbon pollution. But mastering the process on Earth is a huge challenge.

The most common way to achieve fusion energy involves a donut-shaped reactor called a tokamak in which variants of hydrogen are heated to extraordinarily high temperatures to create a plasma.

High-temperature, high-density plasmas, in which long-duration reactions can occur, are vital to the future of nuclear fusion reactors, said Si-Woo Yoon, director of the KSTAR Research Center at the Korea Fusion Energy Institute. (KFE), which achieved the new record.

The Korea Superconducting Tokamak Advanced Research Device (KSTAR), known as the "artificial sun", at the Korea Fusion Energy Institute in Daejeon, South Korea, on January 10, 2022. (Anthony Wallace/AFP/Getty Images)

Sustaining these high temperatures “has not been easy to demonstrate due to the unstable nature of high-temperature plasma,” he told CNN, which is why this recent record is so significant.

KSTAR, KFE's fusion research device referred to as an “artificial sun,” managed to maintain plasma at temperatures of 100 million degrees for 48 seconds during tests conducted between December 2023 and February 2024, exceeding the Previous record of 30 seconds set in 2021.


The KFE scientists said they managed to extend the time by modifying the process, including using tungsten instead of carbon in the "diverters," which remove heat and impurities produced by the fusion reaction.

The ultimate goal is for KSTAR to be able to maintain plasma temperatures of 100 million degrees for 300 seconds by 2026, a "critical point" for scaling up fusion operations, Si-Woo Yoon said.

What scientists are doing in South Korea will contribute to the development of the International Thermonuclear Experimental Reactor in southern France, known as ITER, the world's largest tokamak that aims to demonstrate the viability of fusion.

KSTAR's work "will be of great help to ensure the planned performance of the ITER operation on time and to advance the commercialization of fusion energy," said Si-Woo Yoon.

  • Which is nuclear fusion

This announcement joins a series of other advances in nuclear fusion.

In 2022, scientists at the National Ignition Facility at Lawrence Livermore National Laboratory in the United States made history by successfully completing a nuclear fusion reaction that produced more energy than was used to power the experiment.

In February of this year, scientists near the English city of Oxford announced that they had set a record by producing more energy than ever in a fusion reaction. They produced 69 megajoules of fusion energy over five seconds, roughly enough to power 12,000 homes for the same period of time.

But commercialization of nuclear fusion is still a long way off as scientists work to solve fiendish scientific and engineering difficulties.

Nuclear fusion “is not ready yet and therefore cannot help us with the current climate crisis,” said Aneeqa Khan, a nuclear fusion researcher at the University of Manchester in the United Kingdom.

However, he added, if progress continues, fusion “has the potential to be part of a green energy mix in the second half of the century.”

CNN's Angela Dewan contributed to this report.