The interior of WEST, the tungsten (W) Environment in Steady-state Tokamak, where the fusion record was achieved.
(CEA-IRFM)
A fusion reactor in southern France, called WEST, just achieved an important milestone that brings us one step closer to clean, sustainable, nearly limitless energy.
Scientists at New Jersey's Princeton Plasma Physics Laboratory, who collaborated on the project, announced today that the device created a super-hot material called a plasma that reached 90 million degrees Fahrenheit (50 million degrees Celsius) for 6 straight minutes.
The ultimate goal is to sustain a super-hot plasma for many hours, but 6 minutes is a new world record for a device like WEST. Other nuclear reactors similar to WEST have created hotter plasmas, but they haven't lasted as long.
WEST is what's called a tokamak. It's a donut-shaped fusion reactor the size of an 8-by-8-foot room with 8-foot-tall ceilings, capable of generating the same type of energy that powers our Sun. That's why scientists sometimes call these machines "artificial suns."
"What we are trying to do is create a sun on Earth," Luis Delgado-Aparicio, PPPL's head of advanced projects, told Business Insider. "And that is extremely, extremely challenging," he said, but this new record suggests they're headed in the right direction.
The Sun runs on nuclear fusion (when atomic nuclei combine and release energy) not to be confused with the nuclear fission process (when atomic nuclei split apart and release energy) that powers today's nuclear reactors.
Fusion energy is more powerful than any form of energy we have today. If we can harness that power, 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 that becomes a reality, which is where experimental reactors like WEST come in.
While WEST won't be used to generate fusion for electricity to power homes, it's critical for the research that's laying the groundwork for future commercial reactors.
WEST creates more energy and lays the groundwork for ITER
WEST has a lot in common with ITER, a nearby reactor being built in southern France, which will be the world's largest tokamak capable of self-sustaining burning plasmas when it's finished. Creating that self-heating mix is a crucial step to harnessing the power of fusion for commercial purposes.
However, due to cost and technology setbacks, it's unclear when ITER will be finished. In the meantime, other facilities are conducting experiments to figure out how best to operate the giant reactor. That includes WEST.
The WEST tokamak has a volume of about 530 cubic feet, making it medium-sized compared to ITER. (CEA/C. Roux)
The two reactors are practically neighbors, Delgado-Aparicio said, and the experiments at WEST are directly applicable to ITER.
For fusion to happen on Earth, the fuel needs to reach at least 50 million degrees Celsius. One of the main obstacles fusion power faces is that it takes a tremendous amount of energy to generate those extreme temperatures, and, so far, reactors can't sustain a plasma long enough to gain an energy surplus that could be put toward commercial use. So, for now, fusion reactors typically consume more energy than they produce.
WEST's latest breakthrough was no exception. However, it did generate 15 percent more energy from fusion compared to earlier attempts, PPPL reported in a statement. Moreover, the plasma was twice as dense, another important component of creating more energy.
The key to WEST's record success: tungsten
WEST is helping scientists test the best materials for building the walls inside a fusion reactor, which isn't easy since these environments can reach temperatures more than three times hotter than the sun's center.
Originally, WEST contained carbon walls. While carbon is easy to work with, Delgado-Aparicio said, it also absorbs tritium, a rare hydrogen isotope that fuels the fusion reaction.
"Imagine you have a wall that is not only a wall, but it's some sort of a sponge," he said, "a sponge that absorbs your fuel."
So, in 2012, scientists decided to test a different material for the tokamak's walls, tungsten – the same material that ITER will use for some of its main components.
Because of tungsten's ability to withstand heat without absorbing tritium, Delgado-Aparicio believes it is the ideal material for tokamak walls.
That said, tungsten isn't perfect. One of its downfalls is it can melt and enter the plasma, contaminating it. In turn, this can counteract the process, radiating a lot of energy away and cooling the plasma.
Therefore, to optimize the system, scientists need to understand how exactly tungsten behaves and interacts with the plasma. That's what researchers are doing with WEST.
An image of the plasma from the WEST tokamak. (French Alternatives Energies and Atomic Energy Commission/CEA)
The team at PPPL, for example, modified a diagnostic tool that they used in this latest experiment from WEST. The tool helped the team accurately measure the plasma's temperature to better understand how tungsten migrates from the wall of the device to the plasma.
"We can detect how it moves inside, we can follow it, we can study its transport inside the machine," Delgadot-Aparicio said, which could help build future methods for keeping the plasma free of impurities like blobs of tungsten that cool it down.
"Now we understand how that cooling needs to be taken care of," he said, "and that experience is going to be exported next door to ITER."
WEST and ITER aren't the only reactors that use tungsten.
Commonwealth Fusion Systems (CFS), for example, is using tungsten walls for SPARC, its demonstration fusion reactor. And Korea's KSTAR has a tungsten divertor and recently demonstrated a 30-second, 100-million-degree plasma.
Whether tungsten proves to be the key to unlocking commercial fusion energy remains to be seen.
Commercial fusion energy is still likely decades away, but Delgado-Aparicio thinks they're making steps toward "this big goal of giving energy to humankind."
PPPL said it will publish the results of its experiment in a peer-reviewed journal in a few weeks.
