A new story in Nature reiterates that an Indian-American nuclear scientist’s claims of tabletop fusion are suspect (thanks, Saheli):

Dr. Rusi Taleyarkhan

Several Purdue researchers said Rusi Taleyarkhan, a Purdue professor of nuclear engineering, has stymied their attempts to verify or refute aspects of his controversial “bubble fusion” experiments since late 2003, when he joined Purdue’s faculty. In an article published online Wednesday in the journal Nature, they said their confidence in his work at Purdue and previously at Oak Ridge National Laboratory in Tennessee has been seriously shaken…

Seth Putterman, a professor of physics at the University of California, Los Angeles, who received a $350,000 grant from the Defense Department to try to reproduce Taleyarkhan’s findings, said he has been unable to do so. [Link]

In February 2005, the BBC commissioned a collaboration between Seth Putterman and Ken Suslick (two leading sonoluminescence researchers) to reproduce Taleyarkhan’s work. Using similar acoustic parameters, deuterated acetone, similar bubble nucleation, and a much more sophisticated neutron detection device, the researchers could find no evidence of a fusion reaction. This work was reviewed by a team of four scientists, including an expert in sonoluminescence and an expert in neutron detection, who also concluded that no evidence of fusion could be observed. [Link]

<

p>Taleyarkhan’s paper had skeptics from the beginning — this excerpt is from 2002:

However, many scientists remain sceptical of the results reported by Rusi Taleyarkhan and his colleagues at Oak Ridge National Laboratory in Tennessee, including other researchers at ORNL who tried and failed to repeat the experiments.

The second ORNL team say they used a more sophisticated detection system. But team member Mike Saltmarsh says: “Our experiment saw no evidence for nuclear fusion. This does not prove that no nuclear fusion is going on – it’s virtually impossible to prove a negative – but it does show that if it exists, it is at a very low level…” [Link]

How Dr. Taleyarkhan claims the fusion happened:

In his paper, Taleyarkhan reported producing what he said appeared to be nuclear fusion by bombarding tiny dissolved bubbles in an acetone-based solution with high-intensity sound waves. He claimed the bubbles rapidly expanded and then collapsed, producing a brief flash of light and superhigh temperatures _ a phenomenon called sonoluminescence. He also made the controversial claim that his team detected atomic particles and isotopes, suggesting that nuclear fusion may have occurred. [Link]

The team used a neutron beam to generate microscopic bubbles in acetone, in which the hydrogen atoms had been switched for deuterium, a heavy hydrogen isotope. The team detected light and shock waves from the imploding bubbles, which coincided with emissions of high-energy neutrons. The neutrons had energies of 2.5 million electron volts – the expected energy for neutrons released as deuterium fuses to form helium. They also detected raised levels of tritium, another product of deuterium fusion.

But, though it is theoretically possible for collapsing bubbles to heat to astronomical temperatures, this only happens if they remain perfectly spherical as they implode. Instabilities tend to prevent this and a more realistic temperature may be 10,000 to 20,000 degrees, says Prosperetti. [Link]

<

p>Taleyarkhan is a Parsi from Bombay who studied at IIT Chennai and RPI:

Taleyarkhan earned a bachelor’s degree in mechanical engineering from the Indian Institute of Technology, Chennai, and came to the United States in 1977, earning a master’s degrees in nuclear engineering and business administration and later a doctorate in nuclear engineering, also from Rensselaer.

Son of a prominent Parsi clan of Mumbai, Dr Taleyarkhan’s larger family includes luminaries such as the late Bobby Talyarekhan, the famous radio broadcaster, and Homi Taleyarkhan, a former diplomat. He is married to Navaz Rusi and they have three children, Pervin, Manaz and Meher. [Link]

He also invented variable-velocity rifles (set your phaser on stun, Scotty):

One of his more remarkable inventions is a rifle that can be adjusted so its user fires bullets at varying speeds. The US government has shown great interest in the project because such a non-lethal weapon can be used effectively for peace-keeping, riot-control, and school security. [Link]

“Of course Mother Nature does throw googlies at us, but we believe it can be scaled and are optimistically cautious…” [Link]