A fusion reactor in the south of France, called WEST, has just reached an important milestone that brings us closer to clean, sustainable and almost unlimited energy.
Scientists at the Plasma Physics Laboratory in Princeton, New Jersey, who collaborated on the project, announced today that the device had created an extremely hot material called plasma that reached 90 million degrees Fahrenheit (50 million degrees Celsius) for 6 consecutive minutes.
The ultimate goal is to keep the plasma very hot for several hours, but 6 minutes is a new world record for a device like WEST. Other nuclear reactors similar to WEST created hotter plasmas, but they didn’t last as long.
WEST is what we call a tokamak. It’s a donut-shaped fusion reactor the size of an 8-by-8-foot room with 8-foot-high ceilings, capable of generating the same type of energy that powers our sun. This is why scientists sometimes call these machines “artificial suns.”
Two suns are made of very hot plasma. NASA Solar Dynamics Observatory
“What we’re trying to do is create a sun on Earth,” Luis Delgado-Aparicio, PPPL’s advanced projects manager, told Business Insider. “And it’s extremely, extremely difficult,” he said, but this new record suggests they are moving in the right direction.
The sun works through nuclear fusion (when atomic nuclei combine and release energy) not to be confused with the process of nuclear fission (when atomic nuclei split and release energy) which powers reactors nuclear weapons today.
Fusion energy is more powerful than any form of energy we have today. If we can harness this energy, it could produce almost 4 million times more energy per kilogram of fuel than fossil fuels. Plus, it’s carbon-free.
Significant challenges remain before this becomes a reality, and this is where experimental reactors like WEST come into play.
Even though WEST will not be used to generate merge for electricity to power homes, it is essential for the research that lays the groundwork for future commercial reactors.
WEST creates more energy and prepares the ground for ITER
The WEST tokamak has a volume of approximately 530 cubic feet, making it medium-sized compared to ITER. CEA/C. Redhead
WEST has a lot in common with ITER, a neighboring reactor under construction in the south of France, which will be the world’s largest tokamak capable of burning plasma autonomously once completed. Creating this self-heating mixture is a crucial step in harnessing the power of fusion for commercial purposes.
However, due to cost and technology issues, it is unclear when ITER will be completed. Meanwhile, other facilities are conducting experiments to determine the best way to operate the giant reactor. This includes the WEST.
The two reactors are practically neighbors, Delgado-Aparicio said, and WEST’s experiments are directly applicable to ITER.
For fusion to occur on Earth, it is necessary the fuel must reach at least 50 million degrees Celsius. One of the main obstacles facing fusion power is that it takes a huge amount of energy to generate these extreme temperatures and, so far, reactors cannot maintain a plasma long enough to obtain a surplus energy that could be used for commercial purposes. So, for now, fusion reactors generally consume more energy than they produce.
WEST’s latest breakthrough is no exception. However, the fusion generated 15% more energy compared to previous attempts, PPPL reported in a statement. Additionally, the plasma was twice as dense, another important element for creating more energy.
The key to WEST’s record success: tungsten
Tungsten is a heavy metal that WEST uses in its tokamak because of its heat-resistant properties. Julian Stratenschulte/alliance photo via Getty Images
WEST helps scientists test the best materials to build the walls of a fusion reactor, which is not easy since these environments can reach temperatures more than three times those of the center of the sun.
WEST originally contained carbon walls. Although carbon is easy to work with, Delgado-Aparicio said, it also absorbs tritium, a rare isotope of hydrogen that fuels the fusion reaction.
“Imagine you have a wall that is not just a wall, but is a kind of sponge,” he said, “a sponge that absorbs your fuel.”
So in 2012, scientists decided to test a different material for the tokamak walls, tungsten, the same material that ITER will use for some of its main components.
Tullio Barbui, Novimir Pablant and Luis Delgado-Aparicio review the results of the WEST tokamak experiment. DECTRIS
Because of tungsten’s ability to resist heat without absorbing tritium, Delgado-Aparicio believes it is the ideal material for tokamak walls.
That said, tungsten is not perfect. One of its drawbacks is that it can melt and enter the plasma, contaminating it. In turn, this can thwart the process, radiating a lot of energy and cooling the plasma.
Therefore, to optimize the system, scientists need to understand exactly how tungsten behaves and interacts with plasma. This is what researchers are doing with WEST.
An image of the plasma from the WEST tokamak. Alternative Energies and Atomic Energy Commission (CEA)
The PPPL team, for example, modified a diagnostic tool which they used in this latest WEST experiment. The tool helped the team accurately measure plasma temperature to better understand how tungsten migrates from the device wall into the plasma.
“We can detect how it moves inside, we can track it, we can study its transport inside the machine,” Delgadot-Aparicio said, which could help build future methods to keep the plasma free of impurities such as tungsten drops which cool it. .
“We now understand how this cooling needs to be supported,” he said, “and this experience is going to be exported next to ITER.”
WEST and ITER are not the only reactors to use tungsten.
Commonwealth Fusion Systems (CFS), for example, uses tungsten walls for SPARC, its demonstration fusion reactor. And Korea’s KSTAR has a tungsten divertor and recently demonstrated 30 seconds of plasma at 100 million degrees.
It remains to be seen whether tungsten will prove to be the key to unlocking commercial fusion energy.
Commercial fusion energy is probably still several decades away, but Delgado-Aparicio thinks they’re taking steps toward “this great goal of giving energy to humanity.”
PPPL said it would publish the results of its experiment in a peer-reviewed journal within a few weeks.
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