This device turns neon plasma into natural patterns

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This dot-line pattern was obtained in DBD (left), which is similar to stripe design of the 13-lined ground squirrel (right). (Credit: Hebei University)

Scientists used a device that produces plasma (left) to automatically recreate 3D patterns found in nature, akin to the 13-lined ground squirrel (right). Photo by Hebei University

    From zebra stripes to a honeycomb lattice, nature features breathtaking patterns. Now, physicists based in China have found a way to recreate these natural motifs in 3-D — using just a little electricity. Their new device discharges plasma — air and argon gas charged with electricity — or the same stuff found in neon lights. Using different voltages, the researchers were able to create various 3-D shapes in the plasma.

“To experts, this work could advance the development of plasma physics,” co-inventor Lifang Dong of Hebei University told the NewsHour. “But to non-experts, it could explain a whole range of natural phenomena.”

This work began in 2000, when Dong started noticing natural patterns while working with dielectric barrier discharges (DBD). DBD is an electrical discharge technique utilized in tasks like water purification, dying fabrics and sterilizing medical instruments. But Dong’s creation, reported today in the journal Physics of Plasmas, is the first version able to manipulate patterns in 3-D.

Striped pattern observed in DBD (right), which is similar to those found on zebras (left). (Credit: (left) Goran Tomasevic/Reuters, (right) Lifang Dong, et al)

Striped pattern made by Dong’s DBD device (right), which is similar to those found on zebras (left). Photo by Goran Tomasevic/Reuters (left), Lifang Dong, et al., Physics of Plasmas, 2016 (right)

Human society has spent centuries investigating mysterious shapes in nature.

The Golden Ratio, dating back to ancient Greek mathematicians, is a numerical pattern that dictates everything from how sunflower seeds are arranged to how pinecones get their symmetrical shape. Italian mathematician Leonardo Fibonnaci took things one step further with his Fibonnaci sequence — numbers that follow the Golden Ratio — to explain animal horn growth and shell spirals.

In 1952, Alan Turing, the famous computer scientist, discovered how these patterns appear in nature. He described a reaction-diffusion model, where chemical reactions cause compounds to spread into these patterns. Since its development, Turing’s model has been used to explain leopard spot patterns, chick feathers and the ridges in the mouths of unborn mice.

Honeycomb pattern observed in DBD (right), which is similar to the honeycomb pattern of a beehive (left). (Credit: (left) David W. Cerny/Reuters, (right) Lifang Dong, et al)

Honeycomb pattern observed in Dong’s DBD device (right), which is similar to the honeycomb pattern of a beehive (left). Photo by David W. Cerny/Reuters (left), Lifang Dong, et al., Physics of Plasma, 2016 (right)

Applications of Turing’s model, however, have been confined to one- or two-dimensions, like drawings on pieces of paper. Every element in nature, down to the tiniest molecule, exists in 3-D.

A diagram of the H-gap dielectric barrier discharge machine used by Dong’s research team to create patterns in plasma that are commonly found in nature. (Credit: Dong, et al)

A diagram of the H-gap dielectric barrier discharge machine used by Dong’s research team to create patterns in plasma that are commonly found in nature. Photo by Lifang Dong, et al., Physics of Plasma, 2016

Dong and his team’s research fills this void. Their device placed two copper rods in water on either side of an “H” shaped middle chamber, filled with air and argon gas. Power sent through the copper electrified the water. The contact between the electrified water and the gas-filled gap causes a chemical reaction that creates plasma. The plasma settles in myriad ways depending on the voltage, creating different natural patterns.

Traditional DBDs have just a single gap — like an “I” instead of an “H” — allowing only a 2-D view of pattern. But Dong’s “H” shape has three gaps for the plasma, which allow for a 3-D view of the pattern. It’s like looking at a triple-layer cake. With the single-gap, I-shaped DBD, you can only see the outside of the cake. But with the new H-shaped gap, you can cut into the cake, seeing the layers inside.

This technology can serve more than natural pattern recreation, Dong said. DBDs form the basis for materials called photonic crystals, which in turn, fine tune light for telecommunications products for airplane landing strips, power grids, WiFi, cell phones, microwaves and radar. Dong’s device increases the range of possibilities for photonic crystal engineering.

But for right now, Dong and his team will continue to look for classic patterns from nature.

“I hope that people can take what we’ve developed and use it to better understand the wonders of nature,” Dong said.

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