Originally created 03/09/02

Scientist exhausted, elated with response to fusion research



OAK RIDGE, Tenn. - Rusi Taleyarkhan is 49, suddenly famous and emotionally spent.

"It's been a pressure-cooker for the past one year," said the senior scientist at Oak Ridge National Laboratory who has attracted worldwide attention this week regarding his research on "bubble fusion."

In January 2001, after four years of study and experimentation, Taleyarkhan started seeing "interesting results" in his research with sono-luminescence - a phenomenon in which sound waves produce bubbles that collapse explosively and release energy in the form of light flashes. The feedback gave him confidence that the tabletop experiment might achieve nuclear fusion - the fusing of deuterium atoms at high temperatures.

"I've been living on adrenaline since then," he said.

On Monday, however, the stress became too much. On the same day that Science magazine unexpectedly lifted an embargo on its March 8 publication and broadly released a paper revealing the preliminary - and controversial - results of his research effort, Taleyarkhan was in bed. The long-standing intensity had made him sick.

"I couldn't get off my back," he said.

When he returned to work Tuesday, a couple of hundred e-mails and a bank full of phone messages awaited him. Colleagues from around the world, including friends in his native India, offered congratulations. Others wanted more details on technique and analysis. Reporters posed the obvious questions, most notably, "Is this 'cold fusion' all over again?"

Taleyarkhan said his favorite message was from a one-time skeptic, a fellow scientist who previously had doubted his research in the strongest terms. The message simply congratulated the researcher on his perseverance.

Having the work published was a huge relief. For months the results had been pored over in the peer-review process, every detail challenged by experts inside ORNL and a dozen others retained by Science magazine - one of the world's premier scientific journals. Taleyarkhan and his research team members addressed the questions one by one.

One senior-level administrator in Oak Ridge told Taleyarkhan he had never seen a scientific paper receive such critical attention or so many reviews.

Why? Mostly because of the unfortunate history of tabletop fusion experiments, especially the 1989 fiasco known as "cold fusion."

In that instance, Martin Fleishmann and Stanley Pons of the University of Utah announced prematurely that they had achieved a fusion reaction at room temperature through chemical means and thus set off wild speculation about the possibilities. The celebrated work had not undergone peer review, and when scientists around the globe failed to reproduce their results, the affair turned into one giant embarrassment for the Utah professors and science in general.

Taleyarkhan's research was based on different principles and was decidedly not cold fusion, but there were enough similarities that it would draw the inevitable comparisons. Taleyarkhan knew it would. ORNL management knew it. Science magazine knew it, too.

Everybody knew there'd be plenty of hoopla surrounding the work because once again scientists were claiming to have achieved nuclear fusion in a beaker. Or at least there was evidence that appeared to support such a claim, including the presence of radioactive tritium and the timely release of neutrons from the experimental chamber.

Taleyarkhan said he has performed the bubble experiment more than 100 times, each time taking apart and reassembling the test apparatus.

The experiments rely on what's called "acoustic cavitation," which is the collapse of bubbles formed during the process using sound waves.

According to information from ORNL, cavitation works like this: "When a sound wave propagates through a liquid, the molecules in the liquid are subjected to positive and negative pressures. During the negative pressure phase of the wave, tiny bubbles in the liquid can grow dramatically (up to a factor of 1,000 in volume), since the pressure is below the vapor pressure. When the positive pressure of the sound wave passes, the bubble collapses, and the energy accumulated in the bubble during growth is released."

Taleyarkhan did a couple of things to enhance the research environment. He used acetone, an organic liquid known best to many as nail-polish remover, because it allowed researchers to achieve a high tensile state in the liquid without bubbles collapsing too quickly - a problem known as premature cavitation. Deuterium also was added, thus allowing scientists to study the possible nuclear reaction of deuterium atoms fusing.

The process then was stimulated with strong pulses of neutrons.

The research team reportedly produced bubbles 1,000 times bigger than any achieved by prior studies, with resulting clouds of bubbles interacting and grandly multiplying the implosive force as they collapsed.

Taleyarkhan estimates that the collapsing bubbles generated temperatures approaching 18 million degrees Fahrenheit in pockets of the deuterated acetone - enough to allow the fusion process to take place.

Doesn't that melt everything in sight?

"The bulk of the fluid remains at room-temperature conditions," he said. "You're nucleating certain regions, which form vapor to grow up to astronomical size in proportion to their original size. (The biggest bubbles reach the size of a pencil-top eraser.) And then they implode. It's the implosion phase that is intense compression and intense temperature rises and flashes of light at that point. So it is only those individual regions at any given point in time that are experiencing those extreme temperatures and those extreme states. That's the beauty of this system."

Taleyarkhan came to Oak Ridge National Laboratory 14 years ago after doing advanced fuel designs for Westinghouse Electric Co. in Pittsburgh.

He grew up in a small village called Dohad in western India not far from Bombay. He received his bachelor's degree in engineering at the Indian Institute of Technology and a doctorate in nuclear science and engineering at Rensselaer Polytechnic Institute in New York.