Sonofusion Experiment Produces Results Without External Neutron Source

PhysOrg ^ | January 27, 2006

[ckilmer]

Sonofusion Experiment Produces Results Without External Neutron Source

A team of researchers from Rensselaer Polytechnic Institute, Purdue University, and the Russian Academy of Sciences has used sound waves to induce nuclear fusion without the need for an external neutron source, according to a paper in the Jan. 27 issue of Physical Review Letters.

The results address one of the most prominent questions raised after publication of the team’s earlier results in 2004, suggesting that “sonofusion” may be a viable approach to producing neutrons for a variety of applications.

By bombarding a special mixture of acetone and benzene with oscillating sound waves, the researchers caused bubbles in the mixture to expand and then violently collapse. This technique, which has been dubbed “sonofusion,” produces a shock wave that has the potential to fuse nuclei together, according to the team.

The telltale sign that fusion has occurred is the production of neutrons. Earlier experiments were criticized because the researchers used an external neutron source to produce the bubbles, and some have suggested that the neutrons detected as evidence of fusion might have been left over from this external source.

“To address the concern about the use of an external neutron source, we found a different way to run the experiment,” says Richard T. Lahey Jr., the Edward E. Hood Professor of Engineering at Rensselaer and coauthor of the paper. “The main difference here is that we are not using an external neutron source to kick the whole thing off.”

In the new setup, the researchers dissolved natural uranium in the solution, which produces bubbles through radioactive decay. “This completely obviates the need to use an external neutron source, resolving any lingering confusion associated with the possible influence of external neutrons,” says Robert Block, professor emeritus of nuclear engineering at Rensselaer and also an author of the paper.

The experiment was specifically designed to address a fundamental research question, not to make a device that would be capable of producing energy, Block says. At this stage the new device uses much more energy than it releases, but it could prove to be an inexpensive and portable source of neutrons for sensing and imaging applications.

To verify the presence of fusion, the researchers used three independent neutron detectors and one gamma ray detector. All four detectors produced the same results: a statistically significant increase in the amount of nuclear emissions due to sonofusion when compared to background levels.

As a cross-check, the experiments were repeated with the detectors at twice the original distance from the device, where the amount of neutrons decreased by a factor of about four. These results are in keeping with what would be predicted by the “inverse square law,” which provides further evidence that fusion neutrons were in fact produced inside the device, according to the researchers.

The sonofusion debate began in 2002 when the team published a paper in Science indicating that they had detected neutron emissions from the implosion of cavitation bubbles of deuterated-acetone vapor. These data were questioned because it was suggested that the researchers used inadequate instrumentation, so the team replicated the experiment with an upgraded instrumentation system that allowed data acquisition over a much longer time. This led to a 2004 paper published in Physical Review E, which was subsequently criticized because the researchers still used an external neutron source to produce the bubbles, leading to the current paper in Physical Review Letters.

The latest experiment was conducted at Purdue University. At Rensselaer and in Russia, Lahey and Robert I. Nigmatulin performed the theoretical analysis of the bubble dynamics and predicted the shock-induced pressures, temperatures, and densities in the imploding bubbles. Block helped to design, set up, and calibrate a state-of-the-art neutron and gamma ray detection system for the new experiments.

The research team leaders are all well known authorities in the field of nuclear engineering. Lahey is a fellow of both the American Nuclear Society (ANS) and the American Society of Mechanical Engineers (ASME), and is a member of the National Academy of Engineering (NAE). Block is the longtime director of the Gaerttner Linear Accelerator (LINAC) Laboratory at Rensselaer, and he is also a fellow of the ANS and recipient of their 2005 Seaborg Medal, which recognizes an individual who has made outstanding scientific or engineering research contributions to the development of peaceful uses of nuclear energy. Taleyarkhan, a fellow of the ANS and the program’s director, is currently the Ardent Bement Jr. Professor of Nuclear Engineering at Purdue University. Nigmatulin is a visiting scholar at Rensselaer, a former member of the Russian Duma, and the president of the Bashkortonstan branch of the Russian Academy of Sciences (RAS).

Source: Rensselaer Polytechnic Institute (RPI)

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[leadhead]

This is pretty big. Moving the detectors and getting a proper inverse square law diminishment in the neutron flux density of appropriate magnitude is somewhat incontrovertible

We all knew that.

[TXnMA]

I would give them credit for having the sense (and integrity) to compare the neutron flux with the sonogenerator both on and off. A statistically-significant increase in neutron flux between the "power off" and "power on" states -- combined with the inverse square obervation -- seems pretty convincing to me. (But, then, I'm just a physical chemist...)

[UnbelievingScumOnTheOtherSide]

If there were no fusion, there would be no neutrinos at all and the sun would collapse into a white dwarf immediately.

Star do go through cycles like that - when one fuel depletes and if the star is massing enough to fuse the former waste product. The transitions, such as from fusing hydrogen to fusing helium called the helium flash, are explosive and called novae. The Sun is not sufficiently massive to fuse helium. So it will fuse hydrogen in a shell around the core which moves outward to find fresh hydrogen and grows thinner. The larger the shell, the more heat it produces, causing the sun to gradually expand into a red giant. Comes a point when the shell is so large that the pressure above it is no longer able to sustain fusion. The end of fusion is quite sudden and the infalling of the star's outer layers immediate and catastrophic. There is a huge burst of fusion that throws off 10% of the star into interstellar space. That is a nova. In a star larger than the sun, this flash ignites fusion of helium into carbon in the star's core with a shell of renewed hydrogen into helium fusion around it and the star expands even larger than before since helium fusion is much hotter. Helium fusion does not last nearly as long as hydrogen so there are successive burnouts and reignitions of carbon, oxygen and silicon fusions in shells in stars 100 times as massive as the sun producing ultimately an iron core. Iron (and larger nuclei) fusion consume rather than produce energy. So when an iron star collapses, the infalling is not stopped but accelerated by new fusion. Heavier nuclei are produced in the last fraction of a second of the collapse and then are spewed into space in a recoil known as a supernova. All elements heavier than iron are the result of supernovae which fling a substanial part of their mass into interstellar space before the remnant settles down as a neutron star or black hole.

[Ramcat]

This is the coolest thing I've ever not understood.

Thanks for the laugh.

Are you related to Buster Baxter?

[Don Joe]

OK, I've presented one theory, and you've presented another, and neither of us knows which, if either, is actually the case.

The main difference, as I see it, is that one of us is convinced that he knows with absolute 100% certainty that the theory he's presented really is the case.

However, the paragraph immediately above is speculation on my part.

[Don Joe]

PS: Don't feel bad. The "Global Warming" folks are every bit as certain of their theories too.

The main difference with that arena is that they are obsessed with ramming their theories down the throats of everyone they encounter. This is something I trust isn't an issue with either of the theories you or I have shared.

[norwaypinesavage]

"Perhaps they are coming from the Uranium. Such neutrons would behave according the inverse-square law, only proving that they emanate from the apparatus and are not just background radiation."

True, but they cease emanating when the cavitation source is turned off. Presumably this was done, and reported. If not, this story would not be acceptable at any reliable scientific journal.

[bert]

.....has used sound waves to induce nuclear fusion without the need for an external neutron source, .....

Sonofusion? Those of us here know of it a a zzzzot.

[Churchjack]

Oh...Yeah!

[Owen]

I'm in Utah and I remember the Cold Fusion debacle. The people involved were prestigious and the publication of the work was in peer reviewed journals. The issue was debunked but only because there did not seem to be reliable confirmations. Note, however, that there were always numerous, reputable albeit somewhat unreliable and unrepeatable confirmations. There was not zero ability to confirm. The problem was that confirmations were spotty and never became less so. Money DID flow to try to firm things up. Success at that was never achieved.

I suggest a similar criteria here. Money. Who funded this research? Will they get more money for more -- and this is critical -- will it come from the US fusion research budget. That proved to be a huge issue with Cold Fusion. The big hot fusion projects in the Eastern US burn up hundreds of millions of dollars. If these guys persuade a money diversion, a lot of big projects with big pre-emplaced hot fusion empires are enormously threatened.

[Prince Charles]

Desktop fusion is at hand! Now, where's my lead suit?

[Bob]

Well....that changes everything. NOW I understand. ;^)

The "inverse sqare law" states that the intensity of energy, for example from a light bulb, decreases by the square of a distance change.

If the distance is increased by a factor of 2, the energy received is reduced by a factor of 4, not 2. If the distance is increased by a factor of 3, the energy received is reduced by a factor of 9.

As the distance is increased, the area over which the energy spreads out is much greater than what you might expect.

[Paul C. Jesup]

A team of researchers from Rensselaer Polytechnic Institute, Purdue University, and the Russian Academy of Sciences has used sound waves to induce nuclear fusion without the need for an external neutron source, according to a paper in the Jan. 27 issue of Physical Review Letters.

So the movie "Chain Reaction" is part science fact. Cool.

[William Tell]

norwaypinesavage said: "True, but they cease emanating when the cavitation source is turned off. "

That would be consistent with the idea that the sonic energy was necessary for the creation of the neutrons. The question might remain; are the neutrons the result of "sono-fusion" or "sono-fission"? My comments were just to point out that a source of neutrons was possibly being added to the soup and that this could introduce considerable confusion about the source of any emanating neutrons.

Is there a key indicator that you are aware of which would argue for sono-fusion of hydrogen over some other high-temperature, high-pressure induced reaction?

The initial cold-fusion experiments were basically irreproducible. At least these sonic experiments seem to be something that many labs could reproduce and study. Progress will be quick, I think, if that is truly the case.

[sono]

Cold fusion lives ... obviously not ready for prime time, but no dilithium crystals needed either. If we can survive this decade, we may be energy independent yet.

[shield]

bttt

[William Tell]

WideGlide said: "Well....that changes everything. NOW I understand. ;^) "

The inverse-square law is really pretty easy to understand.

Imagine yourself in a dark room with a candle in the center located twenty feet from a wall. Hold a "shade" consisting of a one-foot square piece of opaque material ten feet from the wall and parallel to the wall.

There will be light from the candle hitting the shade. There will be a shadow on the wall which is twice as big as the shade in both directions, because the wall is twice as far from the candle as the shade. That is, the shadow is a two-foot by two-foot square.

If you then remove the one-foot square, all of the light which was previously hitting the one-foot square will then be hitting the two-foot square area which was previously in shadow. The intensity of light per square foot has decreased by a factor of four, since the original light falling on the shade is now distributed over an area four times as large.

Whatever relative distances are chosen for the experiment, the sides of the shadow will scale with the distance increase and the light falling when the shade is removed will be decreased as it is distributed over an area which is the square of the distance scale.

That is what the "inverse-square" law describes.

[dr_lew]

And yet the eV "temperature" at the center of the sun is only about 1300 eV.

Good point. Doing a little web research, I see that there is a "Gamow peak" between 5 - 30 keV, ( kinetic energy of interaction, ) around which most of the solar fusion reactions occur. As far as I understand it, the peak is produced by the crossing of the exponentially falling frequency of encounters w.r.t. energy, and the exponentially rising cross section of the fusion process due to tunneling. ( BTW, the barrier is actually around 300 keV. )

So solar fusion is dominated by "deep tunneling" reactions, which occur at a very low rate, and this accounts for the very slow rate of hydrogen "burning" in the sun.

[SteveMcKing]

If we can survive this decade, we may be energy independent yet.

Nice as that is, I've begun to theorize that solving any such problem creates many more to fight about. People will always demand more and better stuff at the cost of freedom, taxes, and civility.

Therefore, the problem is not energy- but those who are never happy in life and constantly complaining about things...