Researchers at the Princeton Plasma Physics Laboratory have discovered a new plasma escape mechanism that could significantly improve the performance and lifespan of commercial fusion reactors. By understanding how turbulence affects the confinement of hot plasma, they’ve found a way to better manage the extreme heat and reduce the risk of damage to the reactor’s critical components.
Taming the Plasma Inferno
Fusion: the challenge of taming a star in a way that net energy comes out rather than just in. However, the furious exhaust heat created from the fusing plasma would almost immediately catastrophically damage inside the walls of a commercial size fusion reactor.
Previous research had indicated that the heat would come to bear in a single strip along the divertor ITER plasma scraper which is responsible for flushing out, with the exhaust heat and particles burning plasma. These concerns were that the divertor plates could be quickly damaged meaning lengthy periods of downtime and high repair costs.
But the PPPL team’s new results take a twist. Our simulations show that oftentimes the turbulent disturbances occuring in the magnetic field boundary layer surrounding the plasma are powerful enough to diffuse the heat load and prevent damage of divertor plates. This finding will revolutionize our understanding of the transport processes that govern the heat and particle flows from the core plasma to the walls of a fusion reactor.
Surprise Turbulent Tangle part 2
Centered on the team’s realization of a phenomenon due to the complicated nature of this magnetic field confining, the plasma. In previous studies, the ‘last confinement surface,’ or the boundary between confined plasma and unconfined plasma, was assumed to be unaffected.
However, the fresh simulations show that this region is turbulent because of the plasma turbulence, leading to what the researchers refer to ‘homoclinic tangles.’ When they become tangled in the divertor, these magnetic fields are connected by a series of electrical charges to make it easier for electrons to hop from the edge of the main plasma across to the divertor plasma and extended those heat strike zones further, increasing its coverage area by an estimated thirty percent over previous models.
This is an incredible game-changing discovery. Instead of directing the heat to a very small area, providing prints for wearing out in few cycles, the chaotic knots spread it around preventing most damage to the divertor surface. At the same time, these tangles can slow the rate of abrupt plasma instabilities at the edge — another critical issue for fusion reactor performance.
Conclusion
Researchers believe their recent identification of a novel plasma escape mechanism may change the course of decades-long mission to produce commercial fusion energy. In doing so, they have discovered that turbulence has a significant effect on confining the plasma and thus how to control this turbulence under extreme heat, minimizing the risk of damage to important components of the reactor. Now for the first time in a publication in the journal Plasma Physics and Controlled Fusion we have published experimental evidence which demonstrates that this practical benefit can indeed be achieved with understanding how to optimize and exploit both static and dynamic control. This means in turn that more stable operation may improve machine lifetimes making, once again, development of safe, clean, abundant fusion energy a little closer. This promise of fusion energy could be significant as the world seeks to find a way forward using sustainable sources of energy.
