A Stable Plasma Ring Has Been Created In Open Air For the First Time Ever (futurism.com)

New submitter mrcoder83 shares a report from Futurism: Engineers from the California Institute of Technology (Caltech) have been able to create a stable plasma ring without a container. According to the Caltech press release, it's "essentially capturing lightning in a bottle, but without the bottle." This remarkable feat was achieved using only a stream of water and a crystal plate, made from either quartz and lithium niobate. The union of these tools induced a type of contact electrification known as the triboelectric effect. The researchers blasted the crystal plate with an 85-micron-diameter jet of water (narrower than a human hair) from a specially designed nozzle. The water hit the crystal plate with a pressure of 632.7 kilograms of force per centimeter (9,000 pounds per square inch), generating an impact velocity of around 305 meters per second (1,000 feet per second) -- as fast as a bullet from a handgun. Plasma was formed as a result of the creation of an electric charge when the water hit the crystal surface. The flow of electrons from the point of contact ionizes the molecules and atoms in the gas area surrounding the water's surface, forming a donut-shaped glowing plasma that's dozens of microns in diameter. Caltech posted a video of the plasma ring on their YouTube channel.

Comments

1950s technology

[boudie2]

"Gharib’s team also noticed another peculiar phenomenon: the plasma ring emitted distinct radio frequencies, as evidenced by the high levels of static the engineers’ mobile phones picked up during the experiment. “That’s never been seen before. We think it’s because of the piezo properties of the materials that we used in our experiments,” Pereira explained."
Sounds to me like he's never heard of the plasma speaker.
https://en.wikipedia.org/wiki/...

WTF /.

[drewsup]

I submitted this FOUR DAYS AGO, with links to the Caltech aticle!

Re:"kilograms of force"

[mark-t]

The kilogram and kilogram-force are different units, even if the latter often gets lazily abbreviated in name to the former

That is true, yes. It would be more correct for me to say that the *names* of the units are the same than it to just say (as I had) that the units are the same, but for some reason I didn't think of putting it that way when I was responding, above.

As for Newton having nothing to do with how the kilogram came to be defined today, I know that Newton actually used imperial units. The kilogram-force unit is basically just a metric equivalent to the notion of the concept of pounds of force, which would have actually been the primary expression for the notion of force prior to Newton (long before it was understood that force was actually the product of acceleration and mass, and not just the mass). The creation of the SI unit called a Newton deprecated the notion of using a weight/mass unit to describe force entirely, but the reference to the force experienced by a given mass at 1G persisted, and is still frequently used because it is often more intuitively understood by people without a physics background.

So the expression "kilograms of force" always explicitly refers to the kilogram-force unit, but it is redundant to say that so many kilograms-force of force were used to do work XYZ, so the 'force' suffix on the unit is often dropped from the unit name itself. Since the word appears almost immediately afterwards anyways, no ambiguity about the term's usage remains, but when you see "pounds of force" or "kilograms of force", the actual units being measured to are pound-force and kilogram-force.