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Two of the biggest operational barriers for a nuclear fusion reaction to occur at the “ideal point” have just been overcome.
Just enough 2.2 seconds to, inside the fusion reactor Tokamak DIII-Danother big step has been taken in the production of fusion energy.
Until now it was thought that there was a point – known as the Greenwald limit – above which the density of the plasma could not be increased without it escaping the clutches of the magnets, potentially damaging the reactor. However, it was also known increasing density would be crucial to increase production.
In a study published this Wednesday in Natureresearchers at General Atomics in San Diego, USA, revealed a way to increase density plasma, proving that this can be stable.
Physicists ran the National Fusion Facility’s DIII-D tokamak with a average density 20% above the Greenwald limit.
As New Scientist explains, the team used a higher density in “doughnut-shaped” plasma coreto increase production, allowing it to dip at the closest ends of the containment vessel to descend below the Greenwald limit, thus preventing any plasma leakage.
“These plasmas are very complicated. A small change in conditions leads to a big change in behavior. And experimentally, it’s been more of a trial and error approach, where you try out a lot of different configurations and basically see which one is best,” he explained. Gianluca Sarriresearcher at Queen’s University Belfast, in the United Kingdom.
“It’s about forcing the plasma to do something that is completely against its nature, that it doesn’t want to do,” he added.
The DIII-D’s plasma chamber has an outer radius of just 1.6 meters and it is not yet known whether the same method would work on the new generation tokamak, which will have a radius of 6.2 meters and is expected to create plasma as early as 2025.
“This was done on a small machine. If we take these results and extrapolate them to a larger machine, we hope to put ourselves in a situation where it is possible to obtain gains and a production of significant energy over a significant period of time“, commented Sarri.
According to the researcher, the experience at DIII-D was based on a mix of approaches that are not exactly new, but which, together, seem to have created a promising approach.
The first author of the study, Siye Dingadmitted that – although expensive – it is necessary take the next step: “Currently, the investigation is going in many different directions. My hope is that this article will help focus efforts worldwide.”
