A team of researchers has introduced a method to reduce damage from runaway electrons in tokamak fusion devices. This strategy uses Alfvén waves to interrupt the harmful cycle of runaway electrons. The discovery promises advances in fusion energy and has potential implications for his ITER project underway in France.
Researchers are using Alfvén waves to reduce runaway electrons in tokamak fusion devices, with significant implications for future fusion energy projects, including France’s ITER.
Scientists led by Zhang Liu of the Princeton Plasma Physics Laboratory (PPPL) announced a promising approach to mitigating harmful runaway electrons produced by the destruction of tokamak fusion devices.Key to this approach was the unique type of plasma A wave named after astrophysicist Hannes Alfvén, winner of the 1970 Nobel Prize.
Alfvén waves have long been known to loosen the confinement of high-energy particles in tokamaks, allowing some to escape and reducing the efficiency of the donut-shaped devices. But a new discovery by Chang Liu and his colleagues at General Atomics, Columbia University, and his PPPL reveals beneficial results in the case of runaway electrons.
amazing circular process
Scientists have found that such loosening can allow high-energy electrons to spread out, or scatter, before growing into avalanches that can damage tokamak components. This process turns out to be surprisingly cyclical. Runaways create instability, triggering Alfvén waves and preventing avalanche formation.
“These findings provide a comprehensive explanation for the direct observation of Alfvén waves in destructive experiments,” said Liu, a staff researcher at PPPL and lead author of the paper detailing the results. physical review letter. “This discovery establishes a clear link between these modes and the production of runaway electrons.”
![Zhang Liu](https://scitechdaily.com/images/Chang-Liu-777x564.jpg 777w,https://scitechdaily.com/images/Chang-Liu-400x290.jpg 400w,https://scitechdaily.com/images/Chang-Liu-768x557.jpg 768w,https://scitechdaily.com/images/Chang-Liu-1536x1115.jpg 1536w,https://scitechdaily.com/images/Chang-Liu-2048x1486.jpg 2048w)
Mr. Zhang Liu.Credit: Elle Starkman
Researchers have developed a theory about the remarkable circularity of these interactions. This result was consistent with runaway experiments at the DIII-D National Fusion Facility, a DOE tokamak operated by General Atomics for the Department of Science. Tests of the theory also yielded positive results on Oak Ridge National Laboratory’s Summit supercomputer.
“Chang Liu’s work shows that the population size of runaway electrons can be controlled by the instability caused by the runaway electrons themselves,” said Felix Parra Diaz, head of PPPL’s theory department. “His research is of great interest because it may lead to tokamak designs that naturally reduce damage from runaway electrons due to their inherent instability.”
heat quench
Destruction begins with a sudden drop in temperature of the millions of degrees required for fusion reactions. These droplets, called “thermal quenches,” release a runaway avalanche similar to landslides caused by earthquakes. “Controlling chaos is the biggest challenge to tokamak success,” Liu said.
Nuclear fusion reactions combine lighter elements in the form of plasma (a hot, charged state of matter made up of free electrons and atomic nuclei called ions), releasing vast amounts of energy that power the sun and stars. To do. Therefore, reducing the risk of disruption and runaway electrons would have special advantages for tokamak facilities designed to reproduce the process.
Therefore, reducing the risk of disruption and runaway electrons would have special advantages for tokamak facilities designed to reproduce the process.
![ITER fusion reactor](https://scitechdaily.com/images/ITER-Nuclear-Fusion-Reactor-777x518.jpg 777w,https://scitechdaily.com/images/ITER-Nuclear-Fusion-Reactor-400x267.jpg 400w,https://scitechdaily.com/images/ITER-Nuclear-Fusion-Reactor-768x512.jpg 768w,https://scitechdaily.com/images/ITER-Nuclear-Fusion-Reactor-1536x1024.jpg 1536w,https://scitechdaily.com/images/ITER-Nuclear-Fusion-Reactor-2048x1365.jpg 2048w)
Fusion energy has the potential to become a vital sustainable energy source that complements renewable energy. The world’s largest nuclear fusion experiment, ITER, is being built in France.Credit: ITER Organization
The new approach could influence the development of ITER, the international tokamak being built in France to demonstrate the practicality of fusion energy, and could be a significant step in the development of fusion power plants. There is.
“Our findings set the stage for new strategies to mitigate runaway electrons,” Liu said. All three research centers are currently in the planning stages of an experimental campaign aimed at further developing their surprising and outlandish discoveries.