Brutal Bubbles: Collapsing orbs rip apart atoms (Sonoluminescence, fusion in a jar)

Fill a flask with liquid, rattle it with ultrasonic waves, and hellish microcosms can form within the fluid. Tiny gas bubbles swell and then implode with a fury now revealed to be extreme enough to strip electrons from atoms trapped in the collapse.

The Illinois chemists who have detected that atomic destruction for the first time have also directly measured temperatures of the imploding bubbles. Some of these register at least 15,000 kelvins, a temperature about three times as hot as the Sun's surface.

Researchers have long known that the collapse of ultrasonically generated bubbles emits flashes of light—a phenomenon called sonoluminescence Some scientists even claim that thermonuclear fusion can occur in the implosions.

To explain these phenomena, some physicists have suggested that a plasma—a vapor of electrons and ions—forms in imploding bubbles. No one, however, had evidence of such a condition. Now, David J. Flannigan and Kenneth S. Suslick of the University of Illinois at Urbana-Champaign report light emissions suggestive of a plasma.

Scientists often probe temperatures and other properties of inaccessible objects, such as distant stars, by analyzing the spectra of light the objects emit.

In the past, spectra of sonoluminescence flashes in single bubbles had revealed little, in part because the bubbles may have contained too many atoms and molecules of different energies to allow any discernible sign of a plasma to come through, says Suslick. Furthermore, quantum mechanical effects blur the light pattern.

To minimize problems, he and Flannigan kept the bubble chemistry simple. They injected inert argon gas into a liquid—concentrated sulfuric acid—whose vapor scarcely enters bubbles.

In their implosion experiments, the researchers detected emissions from argon atoms excited to high energies. Those atoms had been hit by high-speed electrons barreling out of tiny "plasma cores," the team argues in the March 3 Nature.

Light doesn't emerge from a plasma's interior. "As with a star," notes Suslick, "you only can measure the temperature of the surface." Such a hot plasma surface, however, suggests "extremely high temperatures at the core," comments William C. Moss of Lawrence Livermore (Calif.) National Laboratory.

Indeed, the new data provide "indirect evidence" of temperatures of hundreds of thousands of degrees K inside the imploding bubbles, adds Lawrence A. Crum of the University of Washington in Seattle.

Rusi P. Taleyarkhan of Purdue University in West Lafayette, Ind., a researcher who has reported that imploding bubbles produced by ultrasound can host what he calls sonofusion, finds the new results encouraging. "High-temperature plasma states … are a necessary precondition for significant and detectable thermonuclear fusion," he says.

Suslick acknowledges that a plasma is a step toward fusion. However, he says, the new work "can neither confirm nor deny" such claims because his experiment and Taleyarkhan's fusion experiments had too many technical differences to permit meaningful comparisons.

Just to mention another anomaly of science, you might want to look at the tunnel diode. It is a commercially produced two-terminal semiconductor in which amplification takes place and the information appears to propaget faster than the accepted speed of light in space.

There appear to be loopholes in some of the scientific laws. Perhaps there is a way to have cold fusion. Nearly every new invention is touted as the cure for all society's ills but never fulfills such promises.

No doubt there are people worried about too cheap a source of energy that would allow someone to leave an unneeded light burning...

This article provides a little more info

Using a technique employed by astronomers to determine stellar surface temperatures, chemists at the University of Illinois at Urbana-Champaign have measured the temperature inside a single, acoustically driven collapsing bubble. Their results seem out of this world. "When bubbles in a liquid get compressed, the insides get hot -- very hot," said Ken Suslick, the Marvin T. Schmidt Professor of Chemistry at Illinois and a researcher at the Beckman Institute for Advanced Science and Technology. "Nobody has been able to measure the temperature inside a single collapsing bubble before. The temperature we measured -- about 20,000 degrees Kelvin -- is four times hotter than the surface of our sun."

This result, reported in the March 3 issue of the journal Nature by Suslick and graduate student David Flannigan, already has raised eyebrows. Their work is funded by the National Science Foundation and the Defense Advanced Research Projects Agency.

Sonoluminescence arises from acoustic cavitation -- the formation, growth and implosion of small gas bubbles in a liquid blasted with sound waves above 18,000 cycles per second. The collapse of these bubbles generates intense local heating. By looking at the spectra of light emitted from these hot spots, scientists can determine the temperature in the same manner that astronomers measure the temperatures of stars.

By substituting concentrated sulfuric acid for the water used in previous measurements, Suslick and Flannigan boosted the brilliance of the spectra nearly 3,000 times. The bubble can be seen glowing even in a brightly lit room. This allowed the researchers to measure the otherwise faint emission from a single bubble.

"It is not surprising that the temperature within a single bubble exceeds that found within a bubble trapped in a cloud," Suslick said. "In a cloud, the bubbles interact, so the collapse isn't as efficient as in an isolated bubble."

What is surprising, however, is the extremely high temperature the scientists measured. "At 20,000 degrees Kelvin, this emission originates from the plasma formed by collisions of atoms and molecules with high-energy particles," Suslick said. "And, just as you can't see inside a star, we're only seeing emission from the surface of the optically opaque plasma." Plasmas are the ionized gases formed only at truly high energies.

The core of the collapsing bubble must be even hotter than the surface. In fact, the extreme conditions present during single-bubble compression have been predicted by others to produce neutrons from inertial confinement fusion.

"We used to talk about the bubble forming a hot spot in an otherwise cold liquid," Suslick said. "What we know now is that inside the bubble there is an even hotter spot, and outside of that core we are seeing emission from a plasma."

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