Posted on 07/25/2002 9:51:18 AM PDT by blam
Thursday, 25 July, 2002, 11:15 GMT 12:15 UK
Fusion experiment disappoints
The idea that we could build nuclear fusion reactors that relied on the extraordinary pressures and temperatures experienced inside tiny, collapsing bubbles in a liquid has suffered a grievous blow. New calculations all but rule out the controversial suggestion, made earlier this year by US and Russian researchers.
We've shown that chemistry occurs within a collapsing bubble, and that it limits the energy available during cavitation
Kenneth Suslick They fired sound waves through acetone, causing minute bubbles in the liquid to form and then collapse at temperatures of millions of degrees to produce small flashes of light.
Their claim was that atomic nuclei could fuse in these conditions, releasing colossal amounts of energy, just as happens in the Sun.
But fresh research from Kenneth Suslick and Yuri Didenko, of the University of Illinois at Urbana-Champaign, now suggests the temperatures inside a single imploding bubble fall several million degrees short of that needed for fusion.
If confirmed, this would be a disappointment. Science is desperately looking for a practical fusion approach that would eliminate the need to use the far dirtier fission process currently employed in the world's nuclear reactors.
Sapping energy
It was in March that Rusi Taleyarkhan, and colleagues from the Oak Ridge National Laboratory in Tennessee and the Rensselaer Polytechnic Institute in New York (both US), reported their "table top" fusion experiment.
Taleyarkhan's work was done with an acetone liquid in which the normal hydrogen atoms had been replaced with deuterium
They claimed that by firing powerful sound waves through acetone they could make tiny bubbles expand and then implode, generating flashes of light and temperatures reaching millions of degrees Celsius.
The phenomenon, known as "sonoluminescence", has long been observed, but Taleyarkhan's team was the first to make strident claims that the conditions inside these "cavitating" bubbles could induce the fusion of heavy hydrogen nuclei. And they claimed the presence of tritium and excess neutrons as proof that fusion had occurred in their experiment.
But when the University of Illinois at Urbana-Champaign team examined closely what was going on inside individual bubbles, it said it found that chemical reactions in the interior of the bubbles were almost certainly sapping the energy available to drive a fusion event.
Controversial research
Illinois's Professor Kenneth Suslick said: "Some researchers have suggested that conditions within a cavitating bubble might be hot enough and have high enough pressure to generate nuclear fusion.
"But we've shown that chemistry occurs within a collapsing bubble, and that it limits the energy available during cavitation."
The original research was published in Science
Instead of the millions of degrees Celsius that are needed to drive a fusion event, Professor Suslick said the temperature inside the cavitating bubbles was only reaching 15-20,000 Celsius.
Taleyarkhan's research went through an exhaustive period of peer review before being published in the journal Science.
However, such was the controversy at the time, and claims that the experiment may have been contaminated, that Science also published material criticising the research simultaneously.
Professor Suslick's work has been published in the journal Nature.
Well, no duh, if it didn't these researchers would be the first to know and the last to tell.
This is about as conclusive as Viking confirming no life exists on Mars. It's not a positive result, but it isn't a negative either.
He was quite a genius, and the real inventor of television, not RCA. I can't understand why his experiments have never been tried to be duplicated. It makes no sense at all for them to have been ignored due to current NIH.
Please see: http://www.farnovision.com/chronicles/fusion/vassilatos.html
Great, hope he benefits from it.
Sounds like some vocational myopia.
The cold fusion dudes were so focused on a physics-based solution that they forgot their chemistry.
Well, for the time being we still have advanced fission reactors to address our energy needs.
There is an active community of amateur open source hobbyists researchers, several of whom have gotten fusors up & running & pumping out neutrons. I don't know how big or powerful the largest ones are, but I don't think anyone's found any hard theoretical limits so far.
Getting one to break even on fusion is at this point a materials problem if I remember correctly. The electrodes start eroding rather quickly when you get to a very high energy level. Looks like one would be quite stunning to see in operation.
The Boy Who Invented Television:
A Story of Inspiration,
Persistence and Quiet Passion
by Paul Schatzkin
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