CONSORTIUM FORMED TO STUDY ACOUSTIC FUSION;

CONSORTIUM FORMED TO STUDY ACOUSTIC FUSION; COULD BE ALTERNATIVE TO OIL, GAS, COAL AND NUCLEAR POWER

The Acoustic Fusion Technology Energy Consortium (AFTEC) has been formed by leading academic and commercial institutions to research and develop acoustic inertial confinement fusion (AICF) and its related science, technologies, and equipment. AFTEC's five founders are (alphabetically): Boston University; Impulse Devices, Inc.; Purdue University; University of Mississippi; and University of Washington Center for Industrial and Medical Ultrasound.

Dr. Wylene Dunbar, Director of AFTEC, today announced the group saying, "Acoustic fusion has an excellent chance of becoming the alternative to oil, gas, coal and nuclear energy for the world's electricity -- if it is funded appropriately."

"If AICF delivers on its potential, the impact would be enormous. Fusion could produce electricity with a process that yields virtually no pollution--just ordinary helium and heat," Dr. Dunbar observed. "With acoustic fusion, the fuel is essentially water, and the cost to build and operate a plant would be a fraction of other alternative energy facilities. Furthermore, the timetable for acoustic fusion is arguably far shorter than all other paths to fusion."

In AICF, sound waves bombard a liquid such as heavy water, to create tiny void "bubbles" or "cavities" of deuterium a/k/a heavy hydrogen. This produces very high temperatures and densities that, when high enough, fuse the heavy hydrogen into helium. That fusion releases enormous heat that could be used to create steam and drive a turbine to produce electricity.

An emerging field, acoustic inertial confinement fusion can already lay claim to significant progress: A multi-institution team led by Dr. Rusi Taleyarkhan has twice documented fusion reactions taking place in an AICF reactor, with the results of those seminal experiments published in two prestigious, peer-reviewed journals, Science 295, 1868 (2002) and Physical Review E 69, 036109 (2004), and receiving publicity worldwide. Under the direction of its President, Ross Tessien, Impulse Devices has recently made available the first commercial research reactor for AICF.

Scientists leading AFTEC's research are preeminent in the field: Dr. R. Glynn Holt, Associate Professor, Department of Aerospace/Mechanical Engineering, Boston University; Dr. D. Felipe Gaitan, (discoverer of single-bubble sonoluminescence, a phenomenon closely related to acoustic fusion research), Chief Scientific Officer, Impulse Devices, Inc.; Dr. Rusi Taleyarkhan, The Ardent Bement Jr. Professor of Nuclear Engineering, Purdue University, and part-time Distinguished staff at a National Laboratory; Dr. Henry Bass, Director of the National Center for Physical Acoustics, University of Mississippi, and F.A.P. Barnard Distinguished Professor of Physics & Astronomy; and Dr. Lawrence A. Crum (leading researcher in the field of high intensity focused ultrasound and past president of The Acoustical Society of America) Professor of Bioengineering and Electrical Engineering and Director, Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington.

Members of AFTEC will work as a team to investigate acoustic fusion, Dr. Dunbar noted, and will consult with National Laboratory scientists for independent verification of positive results, as they are achieved.

"All of the scientists involved with this research appreciate that acoustic fusion is a relatively new field and one that has, so far, received little funding support," Dr. Dunbar stated. "Nevertheless, given AICF's potential for creating a limitless, nonpolluting source of sustainable energy, as well as myriad other applications, they also agree that the investigation of acoustic fusion is critically important and deserving of high priority."

Dr. Dunbar received her Ph.D. in Philosophy from Vanderbilt University and her J.D. from the University of Mississippi.

Public release date: 4-Mar-2002
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Contact: Lisa Onaga
Lonaga@aaas.org
202-326-7088
American Association for the Advancement of Science

Fusion in a flash?
Science researchers report nuclear emissions from tiny, super-hot collapsing bubbles
The embargo on this research by Taleyarkhan et al., and the associated Perspective by Becchetti, has been lifted by the AAAS News & Information Office.
Please Note: Important updated information on super-hot collapsing bubbles is now available. Click here, or contact Lisa Onaga at 202-326-6440, lonaga@aaas.org or scipak@aaas.org.

Whenever additional information on forthcoming papers is made available to the AAAS News & Information Office, an update is posted to EurekAlert!, within the Science Press Package site. Journalists are encouraged to check the site again for any updates before finalizing stories.

A neutron nucleated bubble cloud (size ~6.5mm) in C3D6O just prior to implosive collapse. Fast neutron nucleated bubbles in C3D6O grow from ~10nm to ~1mm in acoustic chamber before imploding to produce neutrons and light.
Courtesy of Oak Ridge National Laboratory, Rensselaer Polytechnic Institute and Russian Academy of Sciences--Rusi P. Taleyarkhan, J. S. Cho, C. D. West, R. T. Lahey, Jr., R. Nigmatulin and R. C. Block.

Full size image available through contact

The dramatic flashing implosion of tiny bubbles--in acetone containing deuterium atoms--produces tritium and nuclear emissions similar to emissions characteristic of nuclear fusion involving deuterium-deuterium reactions. This finding was reported in the 8 March issue of the peer-reviewed journal Science, published by the American Association for the Advancement of Science.

Shock wave 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. Although the high temperatures and pressures within the bubbles would be sufficient to generate fusion, the overall results of the study only suggest, but do not confirm, nuclear fusion in the bubbles’ collapse.

Nuclear fusion joins together light atoms, such as hydrogen, in a reaction that creates a third heavier atom and converts some of the original atoms’ mass into energy. Nuclear fission, the type of reaction currently used in commercial power plants, splits heavy atoms like uranium and releases some of the excess energy stored as mass in the uranium atoms. Scientists have been eager to harness fusion as an energy source, because unlike fission, fusion uses readily available raw material as fuel and produces fewer radioactive waste products.

The experiments performed by the Science researchers suggest that nuclear fusion might occur in bubbles created by “acoustic cavitation,” a phenomenon studied for nearly a century. In acoustic cavitation, the pressure of a sound wave creates and collapses bubbles in a liquid. The first part of the wave is a tension wave, which stretches the liquid and pulls apart a space for bubbles to form when the liquid is bombarded by energetic particles like neutrons. A second compression wave follows close behind, squeezing and bursting the bubbles, which then emit a brilliant but extremely brief flash of light called sonoluminescence.

Sonoluminescence’s exact cause is still somewhat mysterious, but many researchers believe that the shock waves of the collapse generate high temperatures and pressures in the bubble’s gas, which releases a burst of energy. Scientists have learned to trap single bubbles within a sound wave, causing them to swell and shrink and emit light in a regular fashion.

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--if the original bubbles are very small and allowed to grow rapidly before collapse.

Rusi P. Taleyarkhan of Oak Ridge National Laboratory and colleagues devised an experiment to produce these super-hot bubbles, trapping bubbles in deuterated acetone (acetone with its normal hydrogen atoms replaced by deuterium, a heavy hydrogen isotope that can undergo fusion reactions). The experiment’s entire apparatus is well within the bounds of “table-top physics,” about “the size of three coffee cups stacked one on top of the other,” says Taleyarkhan.

Using a pulse of neutrons to first “seed” the tiny bubbles, each no bigger than the period at the end of this sentence, the Science authors then used a sound wave to grow the bubbles rapidly just before their implosion. The process produced stable bubbles that could expand to nearly a millimeter in radius before collapsing, a key part of producing very high pressures and temperatures.

The researchers then searched for signs that fusion might be taking place in the implosions. Deuterium-deuterium fusion reactions create two telltale products: neutrons of a characteristic energy and tritium, another hydrogen isotope. Using very sensitive detectors, Taleyarkhan and colleagues detected higher levels of tritium in samples with extensive bubble implosion. The researchers also observed the emission of neutrons with energy close to 2.5 million electron volts, which is the characteristic neutron energy associated with deuterium-deuterium fusion.

As a part of an elaborate series of control experiments conducted throughout the research, the authors prepared identical experiments in non-deuterated (normal) acetone, and observed no neutron emission or tritium production in these experiments.

Currently, the level of neutron emissions with the characteristic fusion energy appears to be lower than would be expected from the tritium signals observed in the experiment. Further tests are needed to account for this discrepancy, and to verify the observed relations between the neutron emissions, tritium production, and bubble collapse.

If fusion is confirmed in further tests, these bubbles would still have a long way to go before they could be considered as a possible energy source with any commercial value, says Science co-author Richard T. Lahey Jr. of Rensselaer Polytechnic Institute. First of all, the bubble reaction would have to demonstrate net energy gain--that is, it should produce more energy than the energy needed to drive the reaction itself. Second, scientists would have to find a way to make the reaction perpetuate itself in a chain reaction, without constant input from a neutron source.

In the short term, the research may provide a more convenient way for scientists to produce and study nuclear fusion processes in the laboratory, says Fred D. Becchetti of the University of Michigan, in an accompanying Perspective article.

###
The other members of the research team include C.D. West, retired, formerly of Oak Ridge National Laboratory in Oak Ridge, Tennessee, J.S. Cho of Oak Ridge Associated Universities, R.I. Nigmatulin of the Russian Academy of Sciences, Ufa, Russia, and R.C. Block, retired, formerly of Rensselaer Polytechnic Institute in Troy, New York. This research was supported in part by the U.S. Defense Advanced Research Projects Agency (DARPA).
http://www.eurekalert.org/pub_releases/2002-03/aaft-fia030102.php

Evidence for nuclear emissions during acoustic cavitation revisited

R.I. Nigmatulin; R.P. Taleyarkhan; R.T. Lahey
Proceedings of the I MECH E Part A Journal of Power and Energy, 1 September 2004, vol. 218, no. 5, pp. 345-364(20)
This paper extends the experimental and numerical results presented previously and addresses the major criticisms raised. In addition, the most recent results are discussed. In acoustic cavitation experiments with chilled (~0°8 C) deuterated acetone (C3D6O), the production of tritium and 2.45 MeV neutrons [which are characteristic of deuterium-deuterium (D – D) fusion] was observed during vapour bubble implosions in an acoustic pressure field. Similar experiments with deuterated acetone at room temperature ( 20.8 C) and control experiments with normal acetone (C3H6O), at both 0 and 20.8 C, showed no statistically significant increases in either tritium level or neutron emissions. Numerical simulations of the processes that account for the shock waves generated in the liquid and within the collapsing bubbles supported these experimental observations and showed that high densities and temperatures (>108 K) may be achieved during bubble cloud implosions, yielding the conditions required for D – D nuclear fusion reactions. The present paper treats the bubble fusion experiments and theoretical results in greater detail than was possible in the previous publications, contains some refinements, addresses some important questions raised by reviewers and critics and discusses possible applications of this interesting phenomenon.

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