I didn’t expect mayonnaise to be used in this way. In fact, it kind of sounds like a joke, but it’s not. This delicious condiment is helping researchers at Lehigh University in Pennsylvania address one of the great challenges of nuclear fusion. Notably, this exotic application of mayo is related to the inertial confinement fusion, not magnetic confinement.
In inertial confinement fusion, the fuel, which consists of deuterium and tritium nuclei, is encapsulated in a diamond microsphere and placed inside a spherical chamber whose 4-inch-thick aluminum walls contain at least 192 highly sophisticated high-energy lasers. The lasers simultaneously and abruptly focus all their energy on the capsule’s contents so that the fuel is suddenly heated, condensed, and compressed, resulting in the fusion of the deuterium and tritium nuclei.
Magnetic confinement fusion, however, proposes quite a different strategy: confining the plasma containing the deuterium and tritium nuclei to at least 270 million degrees Fahrenheit inside a very intense magnetic field. The kinetic energy the nuclei acquire under these conditions is so high that some overcome their natural electrical repulsion and fuse, releasing a high amount of energy.
Plasma Hydrodynamic Instability Reduces Fusion Energy Yields
Let’s move on to analyze the reaction inside the microsphere containing the fuel for fusion by inertial confinement. When the energy of the lasers causes the fuel to reach the pressure and temperature conditions necessary for the fusion of the tritium and deuterium nuclei, the plasma containing them is subjected to hydrodynamic instabilities. (A quick note: If you want to understand what plasma is, think of it as a scorching gas).
These instabilities can affect the energy yield of the fusion reaction. In this article, we won’t discuss the nature of the hydrodynamic instabilities that plasma is subjected to in order to avoid complicating matters. However, it's important to point out that they’re known as Rayleigh-Taylor instabilities in honor of the two British physicists who first studied them, Lord Rayleigh and Geoffrey Ingram Taylor. Roughly speaking, they occur when materials of different densities coexist, and the pressure and density gradients have opposite directions.
“We use mayonnaise because it behaves like a solid, but when subjected to a pressure gradient, it starts to flow.”
“We use mayonnaise because it behaves like a solid, but when subjected to a pressure gradient, it starts to flow... As with traditional molten metal, if you put stress on mayonnaise, it will start to deform, but if you remove the stress, it goes back to its original shape,” Arindam Banerjee, a professor of mechanical engineering at Lehigh University who led the research, said. The scientist explains that when the mayonnaise receives a certain amount of pressure, it acquires mechanical properties like the plasma in the fuel microsphere.
Accurately understanding plasma dynamics by directly studying the microspheres used in nuclear fusion is impractical due to the complexity and cost. However, researchers can meet this challenge with mayonnaise under perfectly feasible conditions. To make the mayonnaise behave very similarly to the plasma, these scientists built a rotating wheel that allowed them to mimic the flow conditions of the plasma. In this study scenario, they had to get the wheel spinning at the right speed. The mayonnaise takes care of the rest. Ingenious, isn’t it?
The engineers hope their experiment will help them better understand how the transition between the plasma’s elastic and stable plastic phase occurs. This knowledge can help them predict when an instability will happen, and preventing it from occurring can help them maximize the energy yield of the fusion reaction. Researchers still have a lot of work to do on nuclear fusion in general and the inertial confinement strategy in particular, but studies like this give us a glimpse of the future of this technology with healthy optimism.
This article was written by Juan Carlos López and originally published in Spanish on Xataka.
Image | Lawrence Livermore National Laboratory
More info | Lehigh University | Physical Review E
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