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Table Top Fusion Courtesy of Tiny Bubbles
Erik Baard writes: "The peer-reviewed journal Science is carrying a cover story about the possibility of table top fusion. Not cold fusion, mind you, but the apparatus might look that way to some. Oak Ridge and other labs say they have gotten the fingerprints of fusion (neutron production) from collapsing bubbles in liquid, a process that heats a local area to temperatures as hot as the surface of the sun, and releases photons.
The disputes are already here -- notably from Dr. Robert Park of the American Physical Society and from critical reviewers who say they haven't repeated the neutron production. But the authors say the critics didn't calibrate their equipment correctly. Articles regarding the discovery can be found on
Eureka Alert " CD: Looks legit, but Pons and Fleishman (and the University of Utah for that matter) talked a good game. I suppose I'll belive in tabletop fusion when a generator comes atached to my next laptop. The author of this post also has a longer article up at the Village Voice
Sonoluminescence: an Introduction
Single Bubble Sonoluminescence HOWTO
Since sonoluminescence dosent seem to scale up (to my knowledge) this seems like a moot point. It is sort of cool to have a cheap way to study micro-fusion though.
Information wants to be free like speech wants to be free, not like we want beer to be free.
PDF copies can be downloaded from here.
People I respect have been working on this using deuterium. Stainless steel cell, palladium side with the ultrasound attached to it.
Very repeatable response: clean relationships between ultrasound energy, neutrons and helium.
I have thought 'cold fusion' was real from the beginning. It is very normal for scientific breakthroughs to take a long time to reliably replicate: The early work with semi-conductors required elements from particular mines in Chile, etc.
Lew
"The Constitution, the WHOLE Constitution, and nothing but the CONSTITUTION."
You too can make sonoluminescence happen. Try it with some deuterium and see if you can get fusion. Sound complicated, just use this easy to follow guide. It will give you step by step instructions for reproducing that special kind of magic that is sonoluminescence. All you need is:
- sinus generator: (sounds a bit painful)any function generator working around 25kHz, adjustable to +/-1Hz
(+/-10Hz may work, too)
- amplifier: nearly any kind of audio amplifier will do. If you're not sure, measure
the saturation voltage: 40V peak-to-peak should be enough.
- 2-trace oscilloscope
- 2 piezoceramic Transducers (drivers):around d=16mm in diameter, h=8mm thick
- piezoceramic pill-transducer (microphone):around 3mm in diameter, 1mm thick
- three finger clamp
- laboratory stand
- flask:take a 100ml Pyrex/Duran spherical flask, diameter 65mm, with a small neck. An industrial one has poor optical quality, so better take a free blown one.
- coil(s): around 20mH, see text
- resistors: 1M, 10k, 1R
- coaxial cable
- quick-drying epoxy glue
- an eyedropper or a syringe (one of those little do-it-yourself subcutaneous is very good)
- degassed distilled water:
- Pyrex/Duran Erlenmeyer flask (0.5 or 1l) and airtight stopper with pipe, rubber hose and clamp to close it
- aluminium/highgrade steel drinking bottle (0.5 or 1l) with screw cap; one of those found in camping stores, a bare one without varnish
- a bubble
;-)
oh, and it is nice to have:or
- second oscilloscope
- vacuum pump
- high-pass filter
- laser
Go for it kids. By the way, my favourite part is this quote: "Increase the driving voltage until you hear a horrible screeching noise, which sounds like your flask is going to crack. Don't be surprised if it does".I have to fill in some more text here, becasue slashdot sais I have too few characters per line. Well its just a bloody list of things. Of course there won't be much to each line, what do you expect?
"Me and my girl named bimbo . . . limbo . . . spam" - Captain Beefheart.
The surface of the sun is at about 5700K, far below that required for fusion. I thought this meant the science was totally implausible, but it turns out to be an error in the Slashdot summary. ...".
The article claims "simulations also indicate that temperatures inside the collapsing bubbles may reach up to 10 million degrees Kelvin, as hot as the center of the sun." and "Temperatures inside these bubbles can be as high as 5000-7000 degrees Kelvin, about as hot as the sun?s surface. But, recent experiments by a number of researchers suggest that bubble temperatures can reach even higher temperatures--closer to the heat needed for nuclear fusion
Deuterium 'burns' at much lower temperatures than the ordinary hydrogen burning that powers our sun (where reaction rates are so slow it will take billions of years to use up the fuel supply.)
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
Here is a link Science Magazine is providing:
Science Magazine
It has a pdf version of the article in question. Here is the abstract.
The evidence for fusion-capable temperatures inside a sonoluminescing bubble lies in two main categories:
- You can examine the emission spectrum of the bubble. The spectrum is continuous, with a peak which depends on a variety of factors (noble gas content, temperature of the fluid, etc.), so you can try to figure out the temperature based on the emission expected from a blackbody of a similar temperature. The last I heard, the temperature was at least an order of magnitude less than what you would need.
- You can run simulations which make assumptions about the bubble collapse mechanism. If the bubble remains perfectly spherical during the collapse, then you may get the temperatures being quoted in the article. But there are other theories for the collapse, and requiring the bubble to remain perfectly spherical during a violent collapse doesn't seem intuitively obvious to me.
It's been a few years since I worked with this stuff, so take this with a grain of salt, but I'm not optimistic about this paper being validated."she says i'm lousy conversation. as if that's supposed to help."
The idea of fusion in sonoluminescence is nothing new. I sat through a talk on it by some computational hydrodynamics experts from Lawrence Livermore National Lab in 1997 at a the Gaseous Electronics Conference in Hawaii (if you really care, you can probably look up the conference proceedings at http://www.aps.org).
... [pause during the palpable bristling of the audience] ... it's either an implosion or an explosion.'
... yes the temperatures are very low compared to fusion. However, a minuscule amount of fusion (think in terms of one or two atoms per microsecond) would occur and thus there would be measureable neutron flux (in theory). However, in practice, the neutron flux would be so low that it would be nearly impossible to distinguish from the background noise.
... that happens in the core. In fact, it is hotter inside a flourescent light tube (~50K-100K) than at the surface (but the heat conduction is so low that it isn't a safety issue).
The talk was pretty good. Their models were able to explain most of the features reasonably well without having to resort to exotic physics (i.e. quantum electrodynamic weirdness). I mostly remember sitting at this talk because the presenter made a reasonable witty comment (remember, talks like this are usually dry and boring with many audience members nodding off because they are always scheduled after lunch): `Scientists at LLNL have an innately superior understanding of all physics
However, the talk did run into a credibility problem when the presenter said the next step was too look for fusion. Several people in the audience correctly pointed out that the temperatures were several orders of magnitude too low. The presenter's response was that the
Without seeing the paper from the ORNL people, I really can't say if they have upped the sophistication or not though.
By the way, the temperatures at the surface of the sun are only ~6K (except in the wispy corona). Not nearly hot enough for fusion
Kevin
looks like space.com has an article disputing this claim.
"If the creation of nuclear technology became this simple, it not only gives terrorists an easier method to attain nuclear energy, but a way to actually create it themselves."
People like you are going to drive me prematurely bald...
Fusion reactors != fusion bombs
Fustion reactors are so damned far removed from fusion bombs that it's been about 50 years since we developed the second and we still haven't figured out the first. I'm willing to bet it will take at least another 50 years after the development of fusion reactors before we can make a fusion bomb that doesn't require a fission bomb to actually get the thing to go off.
"While it's true that a nuclear explosive based on this current method wouldn't spread as much harmful radiation as a uranium based explosive,"
You're right about that, but you have no idea how right you are.
First and foremost, the act of fission frees neutrons from their parent atoms. A lot of neutrons. Enough neutrons to set off the fission reaction. Fusion generates far fewer free neutrons (if at all, depending on your fuel) because it's busy trying to form atoms instead of breaking them apart.
Secondly, when people think of "radiation" from a bomb they think of the fallout (since the actual radiation from the explosion lasts as long as the actual explosion). Fusion in and of itself has no fallout. The fallout from modern hydrogen bombs is from the fission bomb that's used to set it off. No fission bomb, no fallout.
"it's potential damage far outweighs that of a dirty bomb."
Now here is where you need to lay off the crack pipe.
Getting a fission reaction to start is pretty easy: get a neutron-producer close to a clump of unstable atoms. Getting a fusion reaction to start, on the other hand, requires a LOT of input heat in the beginning in order to generate the plasma the reactions takes place in. So much heat that the pressure at the heart of Jupiter isn't enough to start a sustainable reaction. In the past 50 years the only way we've been able to pull it off is with a fission bomb.
But let's pretend that a pure fusion bomb is possible in the short term. Although it's possible to squeeze a fission bomb into something the size of a suitcase, your average 20 megaton device is more or less a cubic meter in size. But it's only that small because the heat generator is a tiny little suitcase-sized fission bomb. If we try to use a fusion reactor to generate the heat instead of a fission bomb, I don't see the device being small enough to fit into a cargo container (probably the largest possible size for a device to be useful to terrorists).
But what if they try to blow up a fusion power plant? Fission reactors are heavily shielded to keep the inside in. Probable fusion reactors would be heavily shielded to keep the outside out. If a tokomak loses magnetic containment, the plasma expands, cools, and reverts back to a gas. If it loses its physical containment, air gets in, conducts/convects away heat from the plasma, the plasma cools and reverts back to a gas. If you try to blow it up you just end up with a negligible amount of hot gas on top of the explosive.
Personally, I'd be a hell of a lot more frightened of an attack at a coal-fired plant. Have you ever seen what a spark can make coal dust do? Or what about popping off the fuel tanks at a natural gas power plant? And while I'm on the subject of boiling liquid-vapor explosions, oil refineries look awfully unprotected...
I first heard about it when I spent a summer at Lawrence Livermore National Lab two years ago. An abstract of the Nature paper that group at Livermore published is available here
"It take 9 months to bear a child, no matter how many women you assign to the job."
I think this author is giving Pons and Fleischman a bit too much credit. While it is certainly true that both were well-respected chemists, their work on cold fusion was at best sloppy, and at worst, both inaccurate and deceptive.
:
Some facts in the case
1) They used heavy water (D_2O) in their experiments. Steven Koonin, a theoretical nuclear physicist, confronted them at a conference with a simple question : Had they done the simple test of using ordinary water? (Which wouldn't have produced fusion.) The answer was damning : No, they hadn't even thought of it.
2) Their work detecting neutrons (a certain biproduct of fusion, cold or not) from their experiment was presented in a most misleading fashion at conferences. They displayed figures without labels, and did not perform proper calibrations of their detection -- it was impossible to determine whether their "signals" were simply background. (Of course, their detections were orders of magnitude too small -- had the signal been commensurate with the heat produced, they would have been dead from the radioactivity.)
3) Moreover, when confronted with the the fact that their "signals" lacked a crucial feature known as the "Compton edge" (as any physics major has observed this in their labs classes) which must accompany any real signal, they further lopped off their plots so as to show only the spurious peak, making it impossible to realize that they were lacking the Compton edge.
4) They presented their research to the press prior to publication. This turned the scientific process into a media circus, impeding progress, and doing immense damage to the public conception of the scientfic process.
5) Rather than openly describing their methodology (a standard practice in any scientific discipline) to allow other researchers to reproduce their work, they kept their methods secret. I recall several groups were forced to set up their experiments using bits of video footage from the evening news.
6) Later claims by a number of researchers that some extraneous heat was being produced is quite a distinct issue from the original work of Pons and Fleischman. Pons and Fleischman's original claims were much bolder -- they claimed a very large extraneous heat output. It was later determined that they had simply done their calorimetry accounting wrong (a common error in calorimetry, but nonetheless surprising, because they were experts in calorimetry).
In sum, the way Pons and Fleischman conducted their work on cold fusion was a prime example of how science is not to be done. The image of Pons and Fleischman as two revolutionary figures taking on the physics establishment is simply not commensurate with the facts of the case -- they practiced very poor science, by the standards of any scientific discipline.
Bob
Science, like Nature, must also be tamed, with a view turned towards its preservation.
and D-T fusion does produce both ...
but we look for fast (Mev) neutron production to verify fusion, since they're much easier to detect.
this test was what fail F&P as well, BTW.
Working for necessity's mother.
2) To Publish or Not to Publish: Publication is the right option. byt topics/b ubble/1793.pdf
Donald Kennedy, Editor
http://www.sciencemag.org/feature/data/ho
Every once in a while, we at Science receive a paper that causes us to
exercise particular care in handling, because it may be controversial or
because it is importantor both. The paper by Taleyarkhan et al. on p. 1868
of this issue is a case in point. It qualified for careful, responsible
treatment on both counts. And its history with us has exposed some of the
more unusual challenges that can arise in the publication process.
The paper reports experiments in which sonoluminescence is induced in
solutions of deuterated acetone subjected to sound waves and neutron
irradiation. These conditions cause bubbles to grow and then implode,
locally generating high pressures and temperatures and the emission of
sonoluminescent light. The authors present evidence for the production of
tritium in the solution, and for neutron emission coincident with the light
emission. They cautiously interpret these observations as evidence that
deuterium-deuterium fusion occurred in the imploding bubbles. That prospect
naturally encouraged us to treat the paper with care.
After the external review process had been completed, we scheduled the paper
for publication. Then we were contacted by senior science managers at Oak
Ridge National Laboratory (ORNL), who said that certain reservations had
developed
about the findings and their interpretation. In a series of telephone and
e-mail contacts, they urged that we delay the scheduled publication of the
paper. The authors participated in a series of meetings to discuss
objections raised by the ORNL managers, including some findings made by a
second group of scientists who had been asked to perform additional tests,
using the same apparatus but a different detector.
After some negotiation, a compromise was reached in which the authors
responded to criticisms and subsequently made some modifications in the text
to accommodate them. They also agreed to cite a short nonpeer-reviewed
communication in which the second group present measurements that disagree
in some respects with theirs, along with their own response to it. While
these agreements were being reached, Science received communications from
two distinguished scientists in this field, raising objections to the paper
and urging that we reconsider our plans to publish it. And the matter became
even more public on 1 March when Robert Park issued an airy, premature
dismissal from the American Physical Society. By this time, it had become
clear that a number of people didnt want us to publish this paper.
I have been asked, "Why are you going forward with a paper attached to so
much controversy?" Well, thats what we do; our mission is to put
interesting, potentially important science into public view after ensuring
its quality as best as we possibly can. After that, efforts at repetition
and reinterpretation can take place out in the open. Thats where it
belongs, not in an alternative universe in which anonymity prevails, rumor
leaks out, and facts stay inside. It goes without saying that we cannot
publish papers with a guarantee that every result is right. Were not that
smart. That is why we are prepared for occasional disappointment when our
internal judgments and our processes of external review turn out to be
wrong, and a provocative
result is not fully confirmed. What we ARE very sure of is that publication
is the right option, evenand perhaps especially
when there is some controversy.
A reporter also asked me whether this was the only time pressure has been
put on Science not to publish a paper. Although this case is exceptional, it
is not unique; we have been there before. The motivations for urging us not
to publish have varied from one case to another. Often they rest on serious
legitimate scientific differences of opinion, although sometimes that is not
so clear. In this instance, we see no good reason for abandoning our plans
to publish the paper, and we can see no merit whatsoever in the efforts to
discredit it in advance. Both the premature critics and those who believe in
the result would do well to wait for the scientific process to do its work.
The Pons and Fleischmann experiment, if it had actually worked as well as they said it did, would have killed them from the neutron radiation. They didn't bother to do even the most basic accounting of what was going where and when, and they never compared what they measured to what they would have expected to see had they actually produced fusion. Worse, they hid details from their experiment for a considerable period of time, before saying "Wait, you weren't doing it right!" and giving the details of their palladium electrodes when the evidence was mounting against them.
The current experiment, even if it is wrong, at least was performed by experimenters who appear to understand the importance of collecting as much information as possible before hypothesizing models that explain it. The trouble with reproducibility might indicate a problem with their instrument calibration, plus the measured neutron flux and the detected tritium are in disagreement on how much fusion is taking place. However, at least the experimenters acknowledge this, and give a detailed enough description of their setup that others can try to reproduce it. It probably won't pan out, but I won't hold it against them.
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