Nuclear fusion breakthrough as reactor runs seven times hotter than the Sun

This week, Korea's 'artificial Sun' reactor made headlines by officially maintaining plasma at 100 million degrees Celsius for more than 20 seconds.

The researchers at Korea Superconducting Tokamak Advanced Research (KSTAR) achieved an ion temperature of more than 100 million degrees Celsius (180 million degrees Fahrenheit).

The reaction was only stopped after 30 seconds due to technology limits, according to New Scientist.

KSTAR uses magnetic fields to generate and stabilize ultra-hot plasma, with the ultimate aim of making nuclear fusion power a reality.

You can see the footage below showing the reactor run over 24 seconds, and achieving a temperature of more than 10^8 Kelvin – which is more or less equivalent to 100 million degrees Celsius.

Yong-Su Na, one of the KSTAR researchers, told Matthew Sparkes of New Scientist that longer periods should be conceivable in the future after gadget enhancements.

This is a remarkable breakthrough for good reason: it represents a potentially infinite supply of renewable energy that, if successful, might alter the way we power our lives.

But it's also worth noting that KSTAR's rise isn't necessarily a new record, as some media outlets claim.

KSTAR really announced this discovery in 2020, and we covered it at the time. What has changed is that their research report has now been peer-reviewed and published in Nature.

However, in the years since, the KSTAR team has broken their own record, and China's 'artificial Sun' known as EAST (Experimental Advanced Superconducting Tokamak or HT-7U) has gone on to smash both of those.

In 2021, the Chinese Academy of Sciences' fusion machine reached 120 million degrees Celsius (216 million degrees Fahrenheit) and clung onto it for 101 seconds.

That's not to say the KSTAR achievement still isn't huge and worth sharing and celebrating.

Before this breakthrough, the threshold of 100 million degrees hadn't been breached for more than 10 seconds.

The KSTAR. (Korea Institute of Fusion Energy)

"The technologies required for long operations of 100 million-degree plasma are the key to the realization of fusion energy," said nuclear physicist Si-Woo Yoon, a director at the KSTAR Research Centre at the Korea Institute of Fusion Energy (KFE) back in 2020.

"The KSTAR's success in maintaining the high-temperature plasma for 20 seconds will be an important turning point in the race for securing the technologies for the long high-performance plasma operation, a critical component of a commercial nuclear fusion reactor in the future."

An improvement to the Internal Transport Barrier (ITB) modes inside the KSTAR was critical to the time reduction of 20 seconds. Scientists don't fully understand these modes, but on the most basic level, they contribute to control the containment and stability of nuclear fusion reactions.

The KSTAR is a tokamak-style reactor, similar to the one that recently went online in China, that merges atomic nuclei to generate these massive amounts of energy (as opposed to nuclear fission used in power plants, which splits atomic nuclei apart).

Fusion devices like KSTAR use hydrogen isotopes to create a plasma state where ions and electrons are separated, ready for heating – the same fusion reactions that happen on the Sun, hence the nickname these reactors have been given.

As yet, maintaining high-enough temperatures for a long enough period of time for the technology to be viable has proved to be challenging. Scientists are going to need to break more records like this for nuclear fusion to work as a power source – running off little more than seawater (a source of hydrogen isotopes) and producing minimal waste.

Despite all the work that lies ahead in getting these reactors to produce more energy than they consume, progress has been encouraging. By 2025, the engineers at KSTAR want to have exceeded the 100 million-degree mark for a period of 300 seconds.

"The 100 million-degree ion temperature achieved by enabling efficient core plasma heating for such a long duration demonstrated the unique capability of the superconducting KSTAR device, and will be acknowledged as a compelling basis for high performance, steady state fusion plasmas," said nuclear physicist Young-Seok Park, from Columbia University, back in 2020.

The research has been published in Nature.