The aim of researchers to bring nuclear fusion—the process that powers the stars—down to Earth has been bolstered after the Korea Institute of Fusion Energy’s Korea Superconducting Tokamak Advanced Research (KSTAR) reactor maintained super-hot plasma within a magnetic field for 30 seconds.
The achievement is a step forward in scientists’ desire to harness the fusion that occurs at the heart of the Sun, and then reproduce it on Earth in a controlled manner.
Should they succeed, fusion power will provide the world with a safe, sustainable, environmentally responsible, and abundant source of energy.
Fusion is almost the reverse of nuclear fission (which powers the world’s nuclear reactors). Whereas fission consists of the breaking apart of heavy atoms such as uranium, fusion involves the smashing together of light atoms to make heavier atoms and energy.
Fusion is a cleaner process as it creates no radioactive waste, and proceeds with light and abundant materials like hydrogen, which can be obtained from seawater, rather than expensive and rare elements, such as uranium or plutonium.
Theoretically, one liter of water could provide enough raw material for fusion to produce as much energy as the combustion of 300 liters of oil.
Nuclear fusions devices like KSTAR, known as tokamaks, replicate plasma, a state of matter created under the massive gravitational pressure and intense heat of stars like the Sun.
In this super-hot stellar plasma, hydrogen atoms smash together at high velocities creating helium atoms. In the process, these fusions create vast amounts of energy radiated by stars.
To copy this, tokamaks—often referred to as “artificial suns”—must heat heavy helium (deuterium) with lasers to temperatures as high as millions of degrees Fahrenheit, confining it within powerful magnetic fields.
To generate fusion energy, these artificial suns have contained the plasma at these temperatures long enough for atomic nuclei to begin smashing together.
In 2016, KSTAR set a world record for maintaining plasma heated by containing plasma heated to 90 million °F for 70 seconds. This record was broken in 2017 by China’s Experimental Advanced Superconducting Tokamak (EAST) when it sustained 90 million °F plasma for 102 and seconds.
While this temperature is hotter than those in the Sun when fusion processes occur (about 60 million °F), because researchers here on Earth can’t replicate the intense pressure generated by gravity at the heart of a star while on Earth, temperatures in an artificial sun must be much greater to compensate.
That means heating plasma to at least 180 million °F in a tokamak for atomic nuclei to smash together rapidly enough to kick start nuclear fusion.
KSTAR was the first device to break this limit, generating these temperatures in plasma for just 1.5 seconds in 2018.
The team improved on this 2019, maintaining plasma at this temperature for eight seconds. KSTAR upped the ante on this again in December 2020 by generating plasma at this temperature and maintaining it for 20 seconds.
While KSTAR’s new record can’t beat EAST’s record in terms of time, what the researchers on the project have managed to do is heat plasma to this important temperature of 180 million °F.
The KSTAR team was also able to constrain this plasma for a record 30 seconds.
The Korea Institute of Fusion Energy will now seek to improve KSTAR to increase the time that it can maintain plasma at a temperature of 180 million °F. The aim will be to achieve containment of this super-hot plasma for at least 300 seconds.
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