Last year, scientists started up a new type of massive nuclear fusion reactor for the first time, known as a stellarator.
Researchers at the Max Planck Institute in Greifswald, Germany, injected a tiny amount of hydrogen and heated it until it became plasma, effectively mimicking conditions inside the sun.
But since then scientists have been asking whether the ambitious device – named Wendelstein 7-X (W7-X) – works as it is supposed to, producing the right magnetic fields.
Now a research paper has shown tests over the past few months have proven the complex design is working as expected.
The experiment is part of a worldwide effort to harness nuclear fusion, a process in which atoms join at extremely high temperatures and release large amounts of energy.
Advocates acknowledge the technology is likely many decades away, but argue that, once achieved, it could replace fossil fuels and conventional nuclear fission reactors.
Two of the main contenders for nuclear reactors of the future are called tokamaks and stellarators.
Instead of trying to control plasma with just a 2D magnetic field, which is the approach used by the more common tokamak reactors, the stellerator works by generating twisted, 3D magnetic fields.
The new results could be a key step in verifying the feasibility of stellarators for use in future fusion reactors.
Since the machine has been switched on, researchers have been trying to answer the important question of whether or not it is producing the right magnetic fields.
This is crucial because the magnetic field in the machine is the only thing that will trap hot balls of plasma long enough for nuclear fusion to occur.
Physicist Sam Lazerson of the US Department of Energy teamed with the German scientists to test the Wendelstein 7-X (W7-X) fusion energy device.
Now the report, published in Nature Communications, has proven it does work as planned.
‘We’ve confirmed that the magnetic cage that we’ve built works as designed,’ said one of the lead researchers, Sam Lazerson from the US Department of Energy’s Princeton Plasma Physics Laboratory.
Over the coming years W7-X, which is not designed to produce any energy itself, will continue to test the extreme conditions nuclear fusion devices will be subjected to.
The device was first fired up in December last year using helium, which is easier to heat than hydrogen.
‘Here we show the first physics results, obtained before plasma operation: that the carefully tailored topology of nested magnetic surfaces needed for good confinement is realized, and that the measured deviations are smaller than one part in 100,000,’ the authors said.
‘To our knowledge, this is an unprecedented accuracy, both in terms of the as-built engineering of a fusion device, as well as in the measurement of magnetic topology,’ the authors said.
‘This is a significant step forward in stellarator research, since it shows that the complicated and delicate magnetic topology can be created and verified with the required accuracy.’
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