Posted on 01/27/2006 9:32:09 PM PST by 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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Have they proposed a mechanism, or is it just an observation?
A solution of uranium, benzene, and acetone..... Fun. No eating in that laboratory!
No smoking, either.
Sci Ping
Keanu Reeves did this a few years back.
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.
Well....that changes everything. NOW I understand. ;^)
Sonofusion was reported many years ago in IE Magazine. Nobody cared to notice of course, as it was part of the whole CF panoply of nuclear effects, fought tooth and nail by the science good-old-boy network...
If I'm not mistaken it means that big expensive multibureaucratic fusion machine that's slated to be built in france may soon look like a dinasaur
The hunt for a cheap energy replacement for oil is now on about the level of a woolly mammoth hunt for stone age men or a whale hunt for eskimos 400 years ago, or the manhattan project of the 1940's. All the big boys and their research assistants are engaged. Some serious reputations will be made and there is a palpable sense that the beast is nearby.
Psycho_Bunny
I hope my explanation in the previous post helped.
Are you kidding? Cigarette smoke contains benzene which is a known carcinogen. Oh, wait...nevermind.
This is the coolest thing I've ever not understood.
LOL!
Personally, as a soi dissant physicist ( nonpracticing Ph.D. , ) I find the proposed mechanism ridiculous. Consider that the center of the sun is at 10 million Kelvin, and is a very poor producer of fusion, which makes sense when you realize it lasts billions of years without burning out. The human body generates more heat per unit mass than the sun.
There are various superlatives to illustrate the extremity of the solar center environment: A pinhead maintained at that temperature would kill a man a mile away with its radiation ( my uncle told me that years ago - never verified it. ) The radiation pressure alone ( i.e. light pressure, which requires extreme conditions even to be detectable ) would explode the earth ( my calculation . )
Also, perhaps more significantly, note that the hydrogen at the solar center is compressed to 50 times the density of water. Solar collpase is being resisted by the degeneracy pressure of the electrons, which are no longer orbiting the protons, but whizzing about in a background "sea" of negative charge. The protons behave as an ideal gas against this background, mostly "colliding" and being repelled by their coulomb repulsion. Only very, very, occasionally do they have the required energy to approach within the fusion reaction cross section.
The bubble rationale has it that the energy is "focused" and nonthermal, but it has to be thermal, or become thermal very quickly, so my judgment is that the bubble collapses will fall many orders of magnitude short of providing the kinetic energy to fuse protons or deuterons. Obviously, the proponents argue otherwise.
From an experimental point of view, we have this: "In the new setup, the researchers dissolved natural uranium in the solution, which produces bubbles through radioactive decay."
What kind of decay did you say? Producing what particles?
Also note the claim that the neutron radiation is a "statistically significant" increase over background. This is the mantra of ESP researchers.
As to the inverse square verification, I would ask how they could verify this if there signal is much smaller than background, as implied by its relegation to the realm of the "statistically significant".
Anyway, just MHO.
Did you see this one?
This is an extension of the group's previous research, for example see Science Magazine, 2002. An outline of the research that is fairly accessible is at the Wiki Bubble Fusion page.
Psycoliteralactic Protophlagilism !
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