(Image credit: bonchan and DrPixel via Getty Images; collage by Marilyn Perkins)
Nuclear fusion could produce a breakthrough in an unexpected area: mayonnaise production.
In a new study published in May in the journal Physical Review E, scientists placed the creamy condiment in a whisk and set it spinning to see under what conditions it would become fluid.
“We chose mayonnaise because it exhibits the properties of a solid, but when exposed to a pressure gradient, it starts to flow,” explained lead study author Arindam Banerjee, a mechanical engineer at Lehigh University in Pennsylvania.
The process could help clarify the physics of phenomena that occur at the extremely high temperatures and pressures inside fusion reactors, without the need to create such harsh conditions.
Nuclear fusion converts hydrogen into helium in the cores of stars. In theory, this could provide a source of virtually unlimited clean energy on Earth — if the reaction produces more energy than it takes to carry it out.
It's a tall order: Nuclear fusion in stars occurs at temperatures of 27 million degrees Fahrenheit (15 million degrees Celsius), according to NASA. The star's immense gravity forces hydrogen atoms closer together, overcoming their natural repulsion. But on Earth, we don't have that much pressure, so artificial fusion reactors must operate at temperatures 10 times hotter than the sun.
To achieve these astonishing temperatures, scientists use a variety of methods, including inertial confinement.
In the process, physicists freeze pea-sized pellets of gas — typically a mix of heavy isotopes, or varieties, of hydrogen — in metal capsules. They then fire lasers at the pellets, which instantly heats the gas to 400 million F (222 million C) — and, ideally, turns it into a plasma where nuclear fusion can occur, according to the statement.
Unfortunately, the hydrogen gas tends to expand, causing the molten metal to rupture before the hydrogen has a chance to melt. This rupture occurs when the metal capsule becomes unstable and begins to leak.
Bannerjee's team realized that molten metal at lower temperatures behaves like mayonnaise: it can be elastic, meaning it springs back to its original state when acted upon, or plastic, meaning it doesn't spring back, or flow.
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“If you apply stress to mayonnaise, it will start to deform, but once you remove the stress, it will return to its original shape,” he said. “So there is an elastic phase, followed by a stable plastic phase. The next phase is when it starts to flow, and that's where instability begins.”
In the new study, the researchers put mayonnaise in a machine that sped up an emulsion of eggs and oil until it began to flow. They then determined the conditions under which the condiment transitioned between plastic, elastic, and unstable states.
“We have identified the conditions under which elastic recovery is possible and how this effect can be exploited to slow down or completely suppress instability,” Bannerjee said.
The study also showed which conditions promoted greater energy production.
Of course, mayonnaise and super-hot metal capsules are different, so it remains to be seen whether the team's findings can be transferred to a plasma pellet that is significantly hotter than the sun.
Sourse: www.livescience.com
