By Albert Samaha
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According to an article to be published in Science, tabletop fusionthe Holy Grail of new-energy dreamersmay have been achieved, possibly paving the way to cheap, clean power. Scientists say they have discovered that, by using the shock waves of collapsing bubblesyes, bubblesthey can create the heat and compression needed to fuse atoms. If the experiment passes further scrutiny, tabletop fusion could open a means to produce power using common elements like hydrogen, and with far fewer nuclear waste products than traditional uranium-fed fission nuclear power plants.
"I think there's definitely fusion," says the paper's coauthor, Richard T. Lahey Jr., a professor of engineering at Rensselaer Polytechnic Institute. "Don't think I'm being too flippant in saying `Yeah, it's fusion.' There are a lot of ways to create fusion, so that's not a shock. But it is a shock to make fusion so cheaply. You should seewe have something like two coffee cups." Lahey has been pursuing the process for eight years, most intensively for the past three, with funding from Oak Ridge National Laboratory and the Pentagon's Defense Advanced Research Projects Agency. Lahey's former doctoral student Rusi P. Taleyarkhan led the effort at Oak Ridge and secured much of the funding.
To a layman, the claims made by Talevarkhan and Lahey might sound very much like the cold-fusion hype that surrounded Stanley Pons and Martin Fleischmann in 1989. But a key difference here is that computer simulations of shock waves indicate a tiny area of the bubbles may reach up to 10 million degrees Kelvin, as hot as the center of the Sun, where fusion naturally takes place. The phenomenon of sonoluminescenceby which bubbles collapse and produce great heat and flashes of lighthas been observed for a century, and even shrimp use it in nature to stun prey. What is new is simply its application to generate heat for fusion. Rather than water, the "bubble fusion" experiment used the chemical acetone with its normal hydrogen atoms replaced by deuterium, a heavy hydrogen isotope that can undergo fusion reactions.
Still, that hasn't stopped critics from blasting the paper as cold fusion reincarnate. Dr. Robert Park of the American Physical Society, who has for a decade ridiculed new-energy theorists for not publishing papers in respected journals, broke a Science embargo Friday to lash out against the prestigious publication for going ahead with the paper. Park's What's New weekly e-mail bulletin made reference to the "cold fusion fiasco of 13 years ago" when discussing the "bubble fusion" paper.
Science moved up its publication date to an online edition on March 7 and lifted its embargo today because "the reports were getting increasingly distorted," according to Ginger Pinholster, a spokesperson for the magazine and its publisher, the American Association for the Advancement of Science. Pinholster specifically cited Park in the decision. "We knew the paper would be controversial, but it went through a rigorous peer-review process. We felt the best service would be to get it out in the public domain and let scientists debate it and try to reproduce the experiment, and assess if it's a viable energy alternative or not," she explained.
On that note, Lahey is cautious. While he is confident that fusion is occurring more efficiently than in other systems that use accelerators, magnets, and electric arcs, he says, "What do you do with it is not so clear at this point. We can reproduce it, and we know other scientists are going to have to reproduce it in their labs, but the question is, can we scale up and can we sustain a chain reaction? If we could it would solve a tremendous amount of problems. It would really be a boon, but of course that's the next dream."
While, as Pinholster notes, "Dr. Park's analysis didn't undergo peer review," it is drawn from work by two nuclear scientists, Mike J. Saltmarsh and Dan Shapira, who argue they didn't see the fingerprints of fusion in neutron production when they replicated the Oak Ridge experiment. In the review, Shapira and Saltmarsh, also of Oak Ridge, report that they found "no evidence" for one of the telltale products of fusion reactions, and that further research is needed. In their response, Taleyarkhan and colleagues report that Shapira and Saltmarsh did, in fact, detect neutron emissions, but the reviewers had improperly calibrated their detector, and thus misinterpreted the findings. But Taleyarkhan's group agrees that further study is needed.
The attacks outside academia strike Lahey as personally motivated. The U.S. government funds traditional fusion to the tune of hundreds of millions of dollars. "People are worried about the impact these poor little coffee cups are going to make on the Tokamac (a huge machine at the Princeton Plasma Physics Laboratory). That's nonsense. We're not going to affect their budget, and we're at a completely different state of development," Lahey says. Commercial energy production, if possible, is "years away," he says.