Smoke Rings and Nuclear Fusion

Tuckerfan · May 21, 2023

Scientists think that by studying smoke rings they can learn more about nuclear fusion.

New model aims to better understand vortex rings in nuclear fusion

A new mathematical model has been developed that could help improve the viability of nuclear fusion through a better understanding of vortex rings that form in nuclear reactors. The model was developed after researchers observed similarities between them and more common similar phenomena like smoke rings. If successful, the model could help develop methods to compress fuel in reactors better, potentially bringing them closer to reality.

Researchers at the University of Michigan have developed a model that can assist in the design of fuel capsules, reducing the energy lost during the ignition process that causes stars to shine. This model could also prove beneficial to engineers managing fluid mixing after a shock wave, including those designing supersonic jet engines, and physicists studying supernovae.

"These vortex rings move outward from the collapsing star, populating the universe with the materials that will eventually become nebulae, planets, and even new stars—and inward during fusion implosions, disrupting the stability of the burning fusion fuel and reducing the efficiency of the reaction," explains Michael Wadas, a doctoral candidate in mechanical engineering at U-M and corresponding author of the study.

"Our research, which elucidates how such vortex rings form, can help scientists understand some of the most extreme events in the universe and bring humanity one step closer to capturing the power of nuclear fusion as an energy source," he added.

In nuclear fusion reactors, atoms are pushed together until they merge to release exceptional amounts of energy, hence the interest in them. However, this is currently very energy intensive and wasteful as the fuel cannot currently be neatly compressed. Often, as the researchers point out, instabilities in the process can form jets that penetrate into the hotspot of the reaction chamber. This causes some fuel to spurt out between them, much like what would happen if you squished an orange in your hands.

The researchers have discovered that the vortex rings created at the front of these jets bear a mathematical resemblance to smoke rings, the swirls left in the wake of jellyfish, and the plasma rings emitted from a supernova's surface. "Fusion experiments happen so fast that we really only have to delay the formation of the jet for a few nanoseconds," said Eric Johnsen, an associate professor of mechanical engineering at U-M, who supervised the study.

The study brought together the fluid mechanics expertise of Wadas and Johnsen as well as the nuclear and plasma physics knowledge in the lab of Carolyn Kuranz, an associate professor of nuclear engineering and radiological sciences. "In high-energy-density physics, many studies point out these structures, but haven’t clearly identified them as vortex rings," said Wadas.

It is hoped now that researchers can gain insights into the capabilities of vortex rings by utilizing the model as it allows them to determine the maximum energy that can be transported by the ring, as well as the amount of fluid that can be displaced before the flow becomes turbulent and difficult to simulate. At present, the team is conducting experiments to validate the accuracy of the vortex ring model.

You can review the study for yourself in the journal Physical Review Letters.

Study abstract:

Structures evoking vortex rings can be discerned in shock-accelerated flows ranging from astrophysics to inertial confinement fusion. By constructing an analogy between vortex rings produced in conventional propulsion systems and rings generated by a shock impinging upon a high-aspect-ratio protrusion along a material interface, we extend classical, constant-density vortex-ring theory to compressible multifluid flows. We further demonstrate saturation of such vortex rings as the protrusion aspect ratio is increased, thus explaining morphological differences observed in practice.
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Ages ago, I heard a podcast from NPR, I think, where they interviewed ordinary folks who were trying to prove some kind of unconventional science theory. I'm not talking the absolute crazies out there who think that they can some how prove that the cosmos was created after a particular diety gave another one a blowjob, and since she was a spitter, the entire cosmos was created out of man goo. But people if you didn't have a complete understanding of the science involved might think that something was possible.

One of the guys they interviewed was someone who was a business owner, who was moderately wealthy (worth a couple of million), and he was spending big money on trying to prove how smoke rings are a better model for something like the Big Bang theory or something like that. It was one of the things where if you're actually going to try and prove your hypothesis, you'd need a shitload of physicists and gear. I don't remember even enough of the interview to say that if the dude's ideas were anything that you could remotely connect what he was trying to do with this research using the same kind of twisted logic to explain how a Starbucks cup could be on the table in a scene from Game of Thrones (without it being that a member of the cast/crew left it there, and nobody noticed until the show went to air), or if they're actually connected at all.

And I also think about Richard Feynman talking about watching a student at the university cafeteria juggle plates. Feynman noticed the way that the emblem on the plate was spinning in an odd way while the student was juggling it. So, he wondered if he could work out the math involved in it. When he mentioned to one of his friends that he was going to trying and work it out, his friend responded, "Why? It's not important. You'll never be able to use that formula for anything important." Feynman's response was that it was "interesting" to him, and that he wasn't going to work on any more projects that, no matter how important they might be, weren't interesting to him. Feynman later realized that those formulas for the way the emblem spun also gave him clues into how helium behaves at very low temperatures. That was good enough to get him the Nobel Prize in Physics some years later.

So, yeah, maybe we should start doing serious analysis of all kinds of things. Not because we'll prove some strange theory, but because it'll enable us to turn the mathematics behind something that's merely "interesting" to someone into mathematics that explain something entirely different and enable us to do more.

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Smoke Rings and Nuclear Fusion

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Smoke Rings and Nuclear Fusion

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