Engineers have for the first time created a stable ring of plasma in open air. The discovery came as a surprise to Morteza (Mory) Gharib and his fellow researchers at the California Institute of Technology (Caltech). We see plasmas most commonly occurring naturally as lightning or in man-made objects such as plasma cutting tools or fluorescent globes. Plasma doesn’t have a natural shape of its own. Lightning gets its forked appearance as the plasma follows a path of least resistance to the ground and man-made plasmas are usually contained within vacuums or chambers. But Gharib and his team were able to create a stable ring of plasma in the open air just by using a stream of water and a crystal plate. Their surprising findings have been published in the Proceedings of the National Academy of Sciences.
Surprise Discovery Uses Simple Tools
Co-author of the paper, Francisco Pereira of the Marine Technology Research Institute in Italy, a visiting scholar at Caltech describes their success: "We were told by some colleagues this wasn't even possible. But we can create a stable ring and maintain it for as long as we want, no vacuum or magnetic field or anything.” They were able this breakthrough by firing a stream of water at a high-quality crystal plate. The water shoots from a specially designed nozzle that can create an 85-micron-diameter jet which hits the plate at 9,000 pounds per square inch. To put that into context it is a stream of water smaller than a human hair moving as fast as a recently fired bullet. The act of firing the water at the crystal induces the triboelectric effect. This is when an electric charge builds up because of friction with another material. In this particular case, when the water hits the crystal it creates a smooth flow of positively charged ions across the negatively charged surface of the crystal. Where the water hits the crystal and arcs off, “the flow of electrons ionizes the atoms and molecules in the surrounding gas near the surface of the water, creating a donut, or torus, of glowing plasma that is dozens of microns in diameter and visible under a microscope.”
Technique Could Have Application in Energy Storage
The ring created by the jet of water is stable and is able to be maintained as long as the water is flowing. During the experiments, the scientists noticed that the mobile phones were experiencing high levels of static when they were in the same room as the jet setup. They discovered that the plasma actually emits a high frequency.
“That's never been seen before. We think it's because of the piezo properties of the materials that we used in our experiments" said Pereira. While there are no known commercial applications for the torus of plasma at this time. Gharib has applied for a patent on the plasma ring generating technique. He believes there could be some future uses in being able to store energy.