Just seven months after it announced a milestone record for plasma fusion, the Chinese Academy of Sciences has absolutely smashed it.
Their 'artificial Sun' tokomak reactor is has maintained a roiling loop of plasma superheated to 120 million degrees Celsius (216 million degrees Fahrenheit) for a gobsmacking 1,056 seconds, the Institute of Plasma Physics reports.
This also beats the previous record for plasma confinement of 390 seconds, set by the Tore Supra tokamak in France in 2003.
This breakthrough by the EAST (Experimental Advanced Superconducting Tokamak, or HT-7U) reactor is a significant advance for fusion experimentation in the pursuit of fusion energy.
Succeeding in the generation of usable amounts of energy via nuclear fusion would change the world, but it's incredibly challenging to accomplish. It involves replicating the processes that take place in the heart of a star, where high pressure and temperature squeeze atomic nuclei together so tightly that they fuse to form new elements.
In the case of main sequence stars, these nuclei are hydrogen, which fuse to form helium. Since one helium nucleus is less massive than the four hydrogen nuclei that fuse to make it, the excess mass is radiated as heat and light.
This generates a tremendous amount of energy – enough to power a star – and scientists are striving to harness the same process here on Earth. Obviously, there's a significant challenge in creating the heat and pressure that we find in the heart of a star, and there are different technologies to address them.
In a tokamak, plasma is superheated, and confined in the shape of a torus, or donut, by powerful magnetic fields. But maintaining that confined, superheated plasma for longer time frames in order to cultivate longer reaction times is another problem, since superheated plasmas are chaotic and turbulent, prone to instabilities, resulting in leakage.
EAST previously reported a temperature record of 160 million degrees Celsius (288 million degrees Fahrenheit), sustained for 20 seconds (the Sun's core, for context, is 15 million degrees Celsius; the extra heat in a tokamak makes up for the lower pressure).
On 30 December 2021 – just squeaking in for its goal of achieving 1,000 seconds in 2021 – EAST broke the time record, too.
Scientists have been trying to harness the power of nuclear fusion — the process by which stars burn — for more than 70 years. By fusing hydrogen atoms to make helium under extremely high pressures and temperatures, so-called main-sequence stars are able to convert matter into light and heat, generating enormous amounts of energy without producing greenhouse gases or long-lasting radioactive waste.
But replicating the conditions found inside the hearts of stars is no simple task. The most common design for fusion reactors, the tokamak, works by superheating plasma (one of the four states of matter, consisting of positive ions and negatively-charged free electrons) before trapping it inside a donut-shaped reactor chamber with powerful magnetic fields.
Keeping the turbulent and superheated coils of plasma in place long enough for nuclear fusion to happen, however, has been a painstaking process. Soviet scientist Natan Yavlinsky designed the first tokamak in 1958, but no one has ever managed to create an experimental reactor that is able to put out more energy than it takes in.
One of the main stumbling blocks has been how to handle a plasma that's hot enough to fuse. Fusion reactors require very high temperatures — many times hotter than the sun — because they have to operate at much lower pressures than where fusion naturally takes place inside the cores of stars. Cooking plasma to temperatures hotter than the sun is the relatively easy part, but finding a way to corral it so that it doesn’t burn through the reactor walls (either with lasers or magnetic fields) without also ruining the fusion process is technically tricky.
EAST is expected to cost China more than $1 trillion by the time the experiment finishes running in June, and it is being used to test out technologies for an even bigger fusion project — the International Thermonuclear Experimental Reactor (ITER) — that’s currently being built in Marseille, France.
Set to be the world's largest nuclear reactor and the product of collaboration between 35 countries — including every state in the European Union, the U.K., China, India and the U.S. — ITER contains the world's most powerful magnet, making it capable of producing a magnetic field 280,000 times as strong as the one around the Earth. The fusion reactor is expected to come online in 2025, and it will provide scientists with even more insights into the practicalities of harnessing star power on Earth.
China is also pursuing more of its own programs to develop nuclear fusion power — it is conducting internal confinement fusion experiments and is planning to complete a new tokamak by the early 2030s.
Elsewhere, the first viable fusion reactor could be completed in the United States as soon as 2025, and a British company hopes to be commercially generating electricity from fusion by 2030.
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