Bubble Power

In 2002, nuclear engineers Rusi P. Taleyarkhan of Purdue University and Richard T. Lahey Jr. of Rensselaer Polytechnic Institute announced that they had produced thermonuclear fusion by imploding tiny deuterium-rich gas bubbles with sound waves and neutrons. The news about their fusion method–dubbed sonofusion–made headlines worldwide. Yet many skeptics greeted it with scoffing. Now, after repeating the experiments with an improved apparatus, Taleyarkhan and Lahey have more convincing evidence.

In the May 2005 issue of IEEE Spectrum, they discuss their latest experiments in detail and also explain how they plan to turn their tabletop apparatus into a full-scale electricity-generating device. “If this proves possible–and it’s still a big ’if’–sonofusion could become a revolutionary new energy source,” they write.

They also say that other groups may soon have new findings to confirm that sonofusion works. “Now at least five groups–three in the United States and two in Europe–are working on reproducing our sonofusion results,” they write. “Some have apparently already succeeded and are now preparing to publish their findings.”

For more than half a century, thermonuclear fusion has held out the promise of cheap, clean, and virtually limitless energy. But after spending billions of dollars on research, we have yet to identify an economically viable fusion technology that can steadily produce more energy than it consumes.

Today, researchers are using enormous lasers or powerful magnetic fields to trigger limited fusion reactions among deuterium and other hydrogen isotopes. Results are promising and yet still modest–and so the challenge remains.

For several years, Taleyarkhan and Lahey have been working to improve their sonofusion method. They apply sound waves to a deuterium-rich liquid inside which tiny bubbles filled with deuterium vapor grow and then implode. The bubbles’ violent collapse can cause some of the deuterium nuclei they contain to undergo fusion.

“Much more research is required before it is clear whether sonofusion can become a new energy source,” they write. “But then there is only one way we can find out–we will continue making bubbles.”