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Physicists at Lehigh University used a common household object to study the fundamental hydrodynamics of one of the most promising types of fusion reactors. Experiments involving mayonnaise have allowed scientists to better understand what could happen when gas and molten metal mix together under the effect of high acceleration and high centrifugal force.
Who knew that mayo had such an important role to play in a technology that could recreate the power of the sun here on Earth?
Fusion of mayo
Nuclear fusion occurs when two smaller atoms collide at very high energies to create a larger, heavier atom. It is the nuclear process that powers the solar core, which in turn directs life on Earth. One promising method currently used by American scientists to achieve fusion is inertia containment. In research facilities such as the Lawrence Livermore National Laboratory and the Los Alamos National Laboratory, scientists confine a gas – usually isotopes of hydrogen – by freezing it into metal pellets of the size of. a pea. The pellets are placed in a chamber where they are hit by a high-power laser that can generate up to a few million Kelvin (400 million degrees Fahrenheit) – conditions conducive to melting.
Extreme heat causes the gas to expand inside, causing the metal shell to burst before melting is achieved. The process is similar to that of a balloon being squeezed – at one point, the rubber balloon bursts under the pressure of the air inside.
To produce a fusion in an inertial confinement, scientists must first solve the problem of mixing molten metal and heated gas – that's where the mayo comes in. The material properties of the high-temperature mixture are similar to those of the -Temperature, according to Arindam Banerjee, associate professor of mechanical and mechanical engineering at Lehigh University.
Banerjee's field of expertise is the Rayleigh-Taylor instability, a phenomenon that occurs between materials of different densities when the density and pressure gradients are in opposite directions, which creates a stratification unstable.
"In the presence of gravity – or any field of acceleration – the two materials get into one another, like" fingers, "Banerjee said in a statement.
It is extremely difficult to investigate this type of instability because it occurs almost instantaneously and given the large measurement uncertainties of accelerated solids.
For their study, Banerjee and his colleagues poured Hellman's Real Mayonnaise into a plexiglass container, then accelerated the sample into a spinning wheel. The material progress was followed using a high-speed camera at 500 frames / second, whose images were embedded in an image processing algorithm capable of detecting parameters associated with the instability of Rayleigh-Taylor. Growth rates in wavelength and amplitude were finally compared to existing analytical models.
Credit: Arindam Banerjee.
These experiments allowed the research team to visualize both the elastoplastic evolution and the instability of the material. The authors concluded that the onset of instability ("threshold of instability") was related to the size of the amplitude (perturbation) and the wavelength (distance between the crests of a wave) applied.
"The scientific community is questioning whether the growth of instability is a function of initial conditions or a more local catastrophic process," Banerjee said. "Our experiments confirm the previous conclusion: the growth of the interface strongly depends on the choice of initial conditions, such as amplitude and wavelength."
In the future, these results will help researchers design better conditions for inertial containment. Little by little, the world is getting closer to nuclear fusion. On this note, the researchers have already triggered the fusion – it's just that the energy needed to trigger the reaction was greater than the energy produced by it. Among the most promising fusion reactors are the International Thermonuclear Experimental Reactor (ITER) in France and the Wendelstein 7-X reactor. reactor in Germany.
The results appeared in the newspaper Physical examination E.
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