Evoking echoes of the cold fusion fiasco more than a decade ago, Purdue University said Wednesday that it was reviewing the work of physicist Rusi P. Taleyarkhan, who claims to have developed technology to achieve tabletop fusion.
Purdue’s announcement came as the journal Nature released findings Wednesday from its investigation of Taleyarkhan’s widely publicized claim and as a UCLA researcher challenged Taleyarkhan’s report that he had detected fusion byproducts in a key experiment.
Taleyarkhan expressed confidence that Purdue’s review would vindicate his claims, but other researchers said the evidence was likely to be a death knell for the controversial technology, which proponents had claimed would eventually become a major energy source.
It now appears that the technology Taleyarkhan and others proudly call “star in a jar” is probably no more than a flash in the pan.
Taleyarkhan has been “negligent or jumped the gun or concocted data -- one of those -- and has distracted us from a serious problem at the frontiers of research,” said UCLA physicist Seth J. Putterman, who has tried to replicate the research for four years. Taleyarkhan’s three major papers about his research “are all wrong, in my opinion.”
Added retired physicist Michael J. Saltmarsh, who was assigned by the Energy Department’s Oak Ridge National Laboratory to check out Taleyarkhan’s initial report of the technology: “It was very sloppy experimental work, and I simply don’t believe it.... All of his papers are internally inconsistent, and they don’t really make sense.”
The episode has parallels to the 1989 announcement by two Utah researchers, B. Stanley Pons and Martin Fleischmann, that they had created fusion at room temperature by forcing deuterium into special electrodes with an electrical current. Their findings were never replicated.
Taleyarkhan’s claims, first made in 2002, have drawn wide public attention because, unlike cold fusion, they are undergirded by a sound physical theory relating to a technique called sonoluminescence that has been studied for a quarter of a century.
Researchers such as Putterman and chemist Kenneth S. Suslick of the University of Illinois, Urbana-Champaign, have shown that focusing sound waves on a liquid will collapse bubbles, creating very high concentrations of energy.
That technology has found a wide range of applications, including catalyzing chemical reactions, cleaning badly contaminated surfaces and melting fat during liposuction.
Several scientists have speculated that the high temperature and pressure in the imploding bubbles might be sufficient to trigger fusion.
Taleyarkhan reported that he generated bubbles using neutrons to bombard acetone whose hydrogen atoms had been replaced with deuterium, then collapsed the bubbles with a blast of ultrasonic energy.
He said he observed neutrons and tritium, both byproducts of the fusion of deuterium atoms. He submitted a paper to the journal Science, where it was published over the vehement objections of three separate reviewers: Suslick, Putterman and physicist Lawrence A. Crum of the University of Washington.
As with Taleyarkhan’s subsequent papers, the results in that first one “were ambiguous, at best,” Suslick said. “He has never been able to come up with truly definitive results well above background noise.”
Nonetheless, the paper sparked a great deal of interest. The federal Defense Advanced Research Projects Agency awarded $800,000 to Putterman, Suslick and Taleyarkhan to replicate the findings. The British television series “Horizon” gave Putterman $70,000 to repeat the experiment in front of their cameras.
So far, no one has achieved fusion.
One problem, Putterman said, is that the imploding bubbles in acetone reach a temperature of only about 1 million degrees. “For fusion, you need 10 million degrees.”
Taleyarkhan was recruited to Purdue by nuclear engineer Lefteri Tsoukalas to help the university develop expertise in the field.
Tsoukalas told Nature that he was concerned. According to the Nature report, Taleyarkhan removed equipment being used by other Purdue physicists to study the phenomenon and installed it in his own off-campus laboratory, thereby thwarting their research.
He also vociferously opposed publication of the researchers’ negative findings, the report said.
Taleyarkhan and the other Purdue scientists referred all callers to the university’s public relations department, which said it would not address specific issues until the review was completed.
In July 2005, Taleyarkhan asked the Purdue press office to issue a release stating that “peer-reviewed” and “independent” results confirmed his claim of sonofusion, according to the report in Nature. Those results turned out to be in a paper by two members of Taleyarkhan’s lab.
“Presenting that as independent is fraud,” Suslick said.
In January, Taleyarkhan published another paper claiming to have seen neutrons produced by sonofusion. “For the first time, he actually presented some data about the neutrons,” said Brian Naranjo, a physics graduate student in Putterman’s lab.
Using that data, Naranjo calculated the energy signature for the neutrons and compared it to the well-known signature for neutrons produced in fusion. “There is worse than a 1-in-100-million chance that they are the same,” he said.
In fact, the signature is virtually identical to that for neutrons produced by the disintegration of californium-252, a radioisotope commonly used in physics laboratories.
Even his worst critics are not willing to say Taleyarkhan fabricated data, proposing that sloppy experimental work and a strong belief in his cause are at fault.
Putterman, however, notes that Taleyarkhan has said that he observed fusion neutrons six separate times.
“It is hard to imagine how, through pure negligence, he could generate this type of data six times,” Putterman said.