Matter can exist in four distinct phases: solid, liquid, gas, and plasma. Plasmas are made of charged particles—ions and electrons—and occur naturally on Earth as lightning. Now, for the first time, Caltech researchers have created a stable plasma ring in the open air.

Generally, plasmas do not have any shape. Plasmas that created by lighting follows a path of least resistance through the air, creating wildly forking structures. On the other hand, plasmas are constrained by vacuüm chambers or electromagnetic fields.

Morteza (Mory) Gharib (Ph.D. ’83) said, “I was surprised when he and his team were able to generate a stable plasma ring in open air using just a stream of water and a crystal plate.”

A Stable Plasma Ring in Open Air
A torus of plasma, viewed from above. The ring is created by a jet of water striking a crystal plate.
Credit: Mory Gharib/Caltech

“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.”

The flood of water is an 85-micron-width stream impacting from an exceptionally planned spout at 9,000 pounds for every square inch that hits the gem plate with an effective speed of around 1,000 feet for every second. For reference, that is a stream smaller than a human hair moving about as quick as a projectile shot from a handgun.

During the study, scientists experimented with both crystal plates of quartz and lithium niobate. Both plates induce the triboelectric effect, thus built electric charge due to the friction with another material.

At the point when the jet hits the crystal, the water makes a smooth, laminar stream of decidedly charged particles over the adversely charged surface. At the shear locale, where the stream strikes the surface and streams outward crosswise over it, the triboelectric impact triggers a high stream of electrons through the water to its surface. This stream of electrons ionizes the iotas and particles in the encompassing gas close to the surface of the water, making a doughnut, or torus, of shining plasma that is many microns in measurement and noticeable under a magnifying lens.

A Stable Plasma Ring in Open Air
The illustration depicts how the ring is created, in profile. At the shear region, the flow of water induces the triboelectric effect in the crystal, building an electrical charge that flows through the water to its surface.
Credit: Mory Gharib/Caltech

Scientists fired the water jet at surfaces of different textures. They found the smoother the surface, the clearer the structure of the plasma ring. The ring is stable, and as long as the water continues to flow, the ring maintains its shape and size.

Moreover, scientists noticed that their cell phones encountered high levels of radio frequency noise. It means the plasma ring emits distinct radio frequencies.

Pereira said, “That’s never been seen before. We think it’s because of the piezo properties of the materials that we used in our experiments.”

Scientists suggest, currently it does not have any immediate commercial applications. But by seeing it the ability to generate a stable ring of plasma without powerful electromagnetic fields or vacuums suggests the possible use for energy storage.