Free Republic
Browse · Search
News/Activism
Topics · Post Article

Skip to comments.

Desktop fusion is back on the table
Nature Magazine ^ | 10 January 2005 | Mark Peplow

Posted on 01/10/2006 6:15:20 PM PST by PatrickHenry

Can the popping of tiny bubbles trigger nuclear fusion, a potential source of almost unlimited energy? This controversial idea is back on the table, because its main proponent has new results that, he claims, will silence critics. But others say that the latest experiment simply comes with its own set of problems.

The idea is simple enough. Blast a liquid with waves of ultrasound and tiny bubbles of gas are created, which release a burst of heat and light when they implode. The core of the bubble reaches 15,000° C, hot enough to wrench molecules apart. Physicists have even suggested that the intense conditions of this sonoluminescence could fuse atomic nuclei together, in the same process that keeps our Sun running.

Physicist Rusi Taleyarkhan of Purdue University in West Lafayette, Indiana, published the first evidence1 of this 'sonofusion' in 2002; he has been dogged by sceptics ever since.

The underlying physics behind the idea is valid, says Ken Suslick. An expert in sonoluminescence at the University of Illinois in Urbana-Champaign, Suslick tried and failed to replicate Taleyarkhan's first results. If the bubbles' collapse is sufficiently intense, it should indeed be able to crush atoms together. Taleyarkhan just hasn't done enough to prove it, says Suslick.

Needle in a haystack

Taleyarkhan's first experiments were conducted while he was based at Oak Ridge National Laboratory in Tennessee. His idea was to use liquid acetone in which hydrogen atoms had been replaced by their heavier brethren, deuterium. When deuterium nuclei fuse together, they emit a characteristic burst of neutrons. But critics pointed out that Taleyarkhan was using an external source of neutrons to 'seed' the bubbles, and that these were swamping his measurements of neutrons produced by the fusion reaction itself.

"This time round there are no external neutrons," he explains. Instead, his team loaded a mixture of deuterated acetone and benzene with a uranium salt. As the uranium undergoes radioactive decay it releases alpha particles, which can also seed bubble formation, says Taleyarkhan.

"In this experiment we use three independent neutron detectors and a gamma-ray detector," he adds. The results from the four instruments prove that fusion is happening inside his experiment, asserts Taleyarkhan.

Although uranium can release neutrons during fission reactions, Taleyarkhan rules them out because the neutrons he finds bear the energetic hallmark of having come from the fusion of two deuterium nuclei2.

Taleyarkhan's test reactor still puts out a lot less energy than it takes in, making it impractical for generating power. "We have a way to go before we break even," he admits. But in the meantime, he adds, it could be a cheap source of neutrons for analysing the structure of materials. The results are to be published in Physical Review Letters in a few weeks' time.

Unreliable sources

There is one big problem, however: the experiment doesn't always work, and the group is not sure why. Seth Putterman, a physicist at the University of California, Los Angeles, who has also tried to verify some of Taleyarkhan's experiments, notes that the paper does not reveal how many failed runs were required before the team saw a trace of fusion neutrons. "As a paper it doesn't convince me," says Putterman.

Putterman notes that the team did not continuously monitor background neutron levels. Although the neutron count doubles at some points in the experiments, Putterman says that neutrons produced in random showers of cosmic rays, rather than fusion events, could be responsible. But Taleyarkhan points out that the neutron count was smaller in detectors further from the reaction chamber.

To prove that the neutrons are coming from fusion as bubbles burst, Putterman and Suslick suggest that the team closely monitor exactly when the neutrons appear. The current experiment simply counts up the number of neutrons detected over minutes, so correlations with bubble bursts cannot be seen. "The key to improving the signal is timing," says Putterman.

Finding proof

Another obvious way to confirm that fusion is happening would be to look for tritium, a heavier isotope of hydrogen produced by fusion reactions. Tritium leaves a telltale signature of high-energy electrons when it decays and Taleyarkhan claimed to see this in similar previous experiments1,3. But in the current tests, tritium's signature is overwhelmed by ?-decay from the uranium, making it impossible to spot.

Given that Suslick and Putterman have both investigated Taleyarkhan's past claims, they think it odd that they were not consulted by the editors of Physical Review Letters about the paper. "There are other people who are very knowledgeable about this," comments Martin Blume, editor-in-chief of the American Physical Society.

Taleyarkhan says that Suslick and Putterman are welcome to visit his lab to see the results for themselves. Both are eager to go as soon as possible. "We look forward to seeing the experiment run," says Putterman.

[Footnotes are at the end of the original article.]


TOPICS: Culture/Society; Philosophy
KEYWORDS: bubblefusion; coldfusion; fusion; sonofusion; sonoluminescence
Navigation: use the links below to view more comments.
first 1-2021-4041-55 next last
We've had false alarms before, but you never know ...
1 posted on 01/10/2006 6:15:21 PM PST by PatrickHenry
[ Post Reply | Private Reply | View Replies]

To: VadeRetro; Junior; longshadow; RadioAstronomer; Doctor Stochastic; js1138; Shryke; RightWhale; ...
SciencePing
An elite subset of the Evolution list.
See the list's explanation at my freeper homepage.
Then FReepmail to be added or dropped.

2 posted on 01/10/2006 6:16:46 PM PST by PatrickHenry (Felix, qui potuit rerum cognoscere causas.)
[ Post Reply | Private Reply | To 1 | View Replies]

To: PatrickHenry

We're doomed, Patrick. Doomed I tell you.

:)


3 posted on 01/10/2006 6:18:04 PM PST by writer33 (Rush Limbaugh walks in the footsteps of giants: George Washington, Thomas Paine and Ronald Reagan.)
[ Post Reply | Private Reply | To 1 | View Replies]

To: PatrickHenry

I love it - a physicist named Putterman.


4 posted on 01/10/2006 6:20:53 PM PST by SuzyQue
[ Post Reply | Private Reply | To 1 | View Replies]

To: PatrickHenry
Cold fusion and "failed to replicate." Seen it before.
5 posted on 01/10/2006 6:22:12 PM PST by VadeRetro (Liberalism is a cancer on society. Creationism is a cancer on conservatism.)
[ Post Reply | Private Reply | To 1 | View Replies]

To: PatrickHenry
The key theorist behind the 'tiny bubbles' approach to tabletop fusion:


6 posted on 01/10/2006 6:22:30 PM PST by snarks_when_bored
[ Post Reply | Private Reply | To 1 | View Replies]

To: PatrickHenry

bump


7 posted on 01/10/2006 6:23:41 PM PST by Argus
[ Post Reply | Private Reply | To 1 | View Replies]

To: All
I thought this stuff sounded familiar. We had a thread on this topic about six months ago:
Purdue findings support earlier nuclear fusion experiments [Cold Fusion is Back!].
8 posted on 01/10/2006 6:24:22 PM PST by PatrickHenry (Felix, qui potuit rerum cognoscere causas.)
[ Post Reply | Private Reply | To 3 | View Replies]

To: PatrickHenry

You know I always suspected that percolated coffee provided more energy.


9 posted on 01/10/2006 6:24:59 PM PST by kcar (theUNsucks.com)
[ Post Reply | Private Reply | To 1 | View Replies]

To: PatrickHenry

10 posted on 01/10/2006 6:25:54 PM PST by AFreeBird (your mileage may vary)
[ Post Reply | Private Reply | To 1 | View Replies]

To: PatrickHenry

Another obvious problem is that even if fusion does occur, how do you get substantial energy out past the fluid that is sonoluminescing? Sure the fluid itself can transfer the energy, but while it is doing that, it is largely no longer available for the reaction.


11 posted on 01/10/2006 6:27:04 PM PST by lepton ("It is useless to attempt to reason a man out of a thing he was never reasoned into"--Jonathan Swift)
[ Post Reply | Private Reply | To 1 | View Replies]

To: PatrickHenry
You forgot a picture of the experiment...


12 posted on 01/10/2006 6:27:35 PM PST by Turbopilot (Nothing in the above post is or should be construed as legal research, analysis, or advice.)
[ Post Reply | Private Reply | To 1 | View Replies]

To: PatrickHenry; b_sharp; neutrality; anguish; SeaLion; Fractal Trader; grjr21; bitt; KevinDavis; ...
There's been a flood of FReepers joining the FT ping list lately and it's quite likely that I've missed a few, especially if the request was posted on a thread instead of FReepmailed. So, I just wanted to mention that if anyone's requested to join and hasn't been added it's definitely just that I didn't see the request (it's happened a couple times that I know of). Please feel free to request again!

This public service announcement will run for about ten pings or until whenever I get bored posting it. :)

FutureTechPing!
An emergent technologies list covering biomedical
research, fusion power, nanotech, AI robotics, and
other related fields. FReepmail to join or drop.

13 posted on 01/10/2006 6:27:38 PM PST by AntiGuv (™)
[ Post Reply | Private Reply | To 1 | View Replies]

To: PatrickHenry

The fact that Nature touched this one sparks my interest. Has to have a net gain before it's groundbreaking, though. Whoever pulls that one off will probably be remembered as one of the greatest scientists.


14 posted on 01/10/2006 6:28:11 PM PST by mysterio
[ Post Reply | Private Reply | To 1 | View Replies]

To: mysterio
The Nature article says it's going to be published in Physical Review Letters, and that's serious.
15 posted on 01/10/2006 6:31:53 PM PST by PatrickHenry (Felix, qui potuit rerum cognoscere causas.)
[ Post Reply | Private Reply | To 14 | View Replies]

To: PatrickHenry

This one is a lot closer to reality than the Pons-Fleishman experiment. Still, it would be next to impossible to get more energy out than is put in because of the nature of the acoustic mechanism. It might produce some useful physics, perhaps a few papers, maybe a PhD sometime.


16 posted on 01/10/2006 6:31:56 PM PST by RightWhale (pas de lieu, Rhone que nous)
[ Post Reply | Private Reply | To 1 | View Replies]

To: PatrickHenry

Sarcasm or no? I'm unfamiliar with the physics publications. I am in the biochemistry microcosm.


17 posted on 01/10/2006 6:35:09 PM PST by mysterio
[ Post Reply | Private Reply | To 15 | View Replies]

To: PatrickHenry

'sonofusion"? "sonoluminescence"?

Sonovabitch! Here we go again!


18 posted on 01/10/2006 6:35:13 PM PST by adorno
[ Post Reply | Private Reply | To 1 | View Replies]

To: mysterio
No sarcasm.
19 posted on 01/10/2006 6:36:34 PM PST by PatrickHenry (Felix, qui potuit rerum cognoscere causas.)
[ Post Reply | Private Reply | To 17 | View Replies]

To: VadeRetro; PatrickHenry
Given that Suslick and Putterman have both investigated Taleyarkhan's past claims, they think it odd that they were not consulted by the editors of Physical Review Letters about the paper.

Not peer-reviewed?

20 posted on 01/10/2006 6:41:18 PM PST by phantomworker ("Compared to what we ought to be, we are only half awake..." --William James)
[ Post Reply | Private Reply | To 5 | View Replies]


Navigation: use the links below to view more comments.
first 1-2021-4041-55 next last

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.

Free Republic
Browse · Search
News/Activism
Topics · Post Article

FreeRepublic, LLC, PO BOX 9771, FRESNO, CA 93794
FreeRepublic.com is powered by software copyright 2000-2008 John Robinson