Sonofusion

The Star in a Jar

History of Sonofusion • Patents & Commercial Efforts • Sonofusion Calculations • Other Links

Sonoluminescence occurs when sonic pressure waves cause the growth and subsequent collapse of microscopic bubbles. Due to the high pressures released during the collapse of the bubbles, energy can be emitted in the form of light, hence sonoluminescence. If the energy is great enough, it is thought that fusion reactions can be initiated, or sonofusion. Sonofusion or bubble cavitation is thought to be more correctly termed acoustic inertial confinement fusion (acoustic ICF).

History of Sonofusion

The earliest reference I have found on a sonofusion-type process is a patent by Hugh G. Flynn, a professor at the University of Rochester. Flynn passed away in 1997.

US 4,333,796: Method of generating energy by acoustically induced cavitation fusion and reactor therefor.
Nuclear fusion energy prodn. by liquid cavitation - using acoustic devices to produce alternating pressure pulses in liquid metal containing hydrogen isotopes.
Filed: 1978-05-19. Published 1982-06-08.
Abstract: Two different cavitation fusion reactors (CFR's) are disclosed. Each comprises a chamber containing a liquid (host) metal such as lithium or an alloy thereof. Acoustical horns in the chamber walls operate to vary the ambient pressure in the liquid metal, creating therein small bubbles which are caused to grow to maximum sizes and then collapse violently in two steps. In the first stage the bubble contents remain at the temperature of the host liquid, but in the second stage the increasing speed of collapse causes an adiabatic compression of the bubble contents, and of the thin shell of liquid surrounding the bubble. Application of a positive pressure on the bubble accelerates this adiabatic stage, and causes the bubble to contract to smaller radius, thus increasing maximum temperatures and pressures reached within the bubble. At or near its minimum radius the bubble generates a very intense shock wave, creating high pressures and temperatures in the host liquid. These extremely high pressures and temperatures occur both within the bubbles and in the host liquid, and cause hydrogen isotopes in the bubbles and liquid to undergo thermonuclear reactions. In one type of CFR the thermonuclear reaction is generated by cavitation within the liquid metal itself, and in the other type the reaction takes place primarily within the bubbles. The fusion reactions generate energy that is absorbed as heat by the liquid metal, and this heat is removed from the liquid by conduction through the acoustical horns to an external heat exchanger, without any pumping of the liquid metal.

A discussion of this patent has been given by Larry Crum.

The earliest reference to the term "sonofusion" seems to be by Steven E. Jones, a professor at Brigham Young University. A graduate student of his at BYU, Jeannette Lawler, was involved in a search for "sonofusion" in D2O as early as December 10, 1992. A theoretical discussion was given in 1992 by Terry Bollinger. Jones provided another overview in 1995.

In 1992, Seth Putterman of UCLA indicated that his group had reached 100,000 C in sonoluminescence experiments, and thought 1 million C was possible. Roger Stringham claimed to have produced confined nuclear fusion via ultrasound in 1993. Also in 1993 Fukushima and Yamamoto wrote an article entitled "Sonofusion: Maximum Temperature Hot Spots".

Seth Putterman applied for a patent for a sonofusion device in 1994, which was granted in 1997.
US 5,659,173: Converting acoustic energy into useful other energy forms
Inventors: Seth J Putterman, Bradley Paul Barber, Robert Anthony Hiller, Ritva Maire Johanna Lofstedt
Filed: 1994-02-23. Published 1997-08-19.
Converting acoustic energy into different energy form - by applying controlled resonant acoustic energy to gas bubble in liq.
Abstract: Sonoluminescence is an off-equilibrium phenomenon in which the energy of a resonant sound wave in a liquid is highly concentrated so as to generate flashes of light. The conversion of sound to light represents an energy amplification of eleven orders of magnitude. The flashes which occur once per cycle of the audible or ultrasonic sound fields can be comprised of over one million photons and last for less 100 picoseconds. The emission displays a clocklike synchronicity; the jitter in time between consecutive flashes is less than fifty picoseconds. The emission is blue to the eye and has a broadband spectrum increasing from 700 nanometers to 200 nanometers. The peak power is about 100 milliWatts. The initial stage of the energy focusing is effected by the nonlinear oscillations of a gas bubble trapped in the liquid. For sufficiently high drive pressures an imploding shock wave is launched into the gas by the collapsing bubble. The reflection of the shock from its focal point results in high temperatures and pressures. The sonoluminescence light emission can be sustained by sensing a characteristic of the emission and feeding back changes into the driving mechanism. The liquid is in a sealed container and the seeding of the gas bubble is effected by locally heating the liquid after sealing the container. Different energy forms than light can be obtained from the converted acoustic energy. When the gas contains deuterium and tritium there is the feasibility of the other energy form being fusion, namely including the generation of neutrons.

Putterman later (2005) developed a pyroelectric crystal fusion device.

In 1994, William C Moss examined simulations of sonoluminescence that could theoretically produce deuterium fusion reactions. Phys. Fluids 6(9) 2979 (01 Sep 1994)

Joseph A Clark of the US Navy received a patent that teaches a method of sonoluminescence. The patent refers to Hugh Flynn's earlier patent, but does not make any reference to fusion in the abstract.
US 5,858,104. System for focused generation of pressure by bubble formation and collapse
Filed: 1995-12-21, Published: 1999-01-12.
Acoustically-driven bubble pressure generating system which creates sonoluminescence phenomena - has pulsed acoustic shock wave introduced into liquid and reflected and focussed onto object to form bubble expanding around object and collapsing in response to static pressure.
Abstract: A pressure generating system uses a shock wave chamber filled with a liquid pressurized to a static pressure different from ambient atmospheric pressure. Once a a preferred location is established in the chamber, a pulsed compressional acoustic shock wave introduced into the liquid is reflected from a free surface of the liquid as a dilatation wave focused on a point at which a bubble forms and expands about an object. The static pressure causes the bubble to collapse around the object to generate a high pressure thereat.

Possibly related experimental evidence for excess heat generation in ultrasonically-driven cavitation in heavy water is claimed in an EPRI Report (George & Stringham, 1996) by E-Quest Sciences, although attributed to a nuclear micro-fusion process.
George, D.R., and Stringham, R.S. (1996) "Technical report on the demonstration of new technology producing heat and nuclear products via cavitation induced micro-fusion in the E-Quest Sciences Mark II research device", EPRI Project Final Report, Work Order #3170-28, Palo Alto, CA, May 1996.

The most recent stir about sonofusion has been made by Rusi P Taleyarkhan, currently of Purdue University. It appears that Taleyarkhan and Lahey were interested in sonoluminescence prior to the first sonofusion paper, and were making an effort to increase the energy released via the process.
Role of very-high-frequency excitation in single-bubble sonoluminescence, Moraga FJ, Taleyarkhan RP, Lahey RT Jr, Bonetto FJ., Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 2000 Aug;62(2 Pt A):2233-7.

Taleyarkhan first published on the sonofusion phenomenon in Science. It is rumoured that there was controversy among 13 or 14 reviewers over its publication
Evidence for Nuclear Emissions During Acoustic Cavitation.
R. P. Taleyarkhan, C. D. West, J. S. Cho, R. T. Lahey Jr., R. I. Nigmatulin, R. C. Block
Science, Vol 295, Issue 5561, 1868-1873, 8 March 2002
Abstract: In cavitation experiments with deuterated acetone, tritium decay activity above background levels was detected. In addition, evidence for neutron emission near 2.5 million electron volts was also observed, as would be expected for deuterium-deuterium fusion. Control experiments with normal acetone did not result in tritium activity or neutron emissions. Hydrodynamic shock code simulations supported the observed data and indicated highly compressed, hot (106 to 107 kelvin) bubble implosion conditions, as required for nuclear fusion reactions.

In the paper, the authors described how bubbles were created via nucleation by fast neutrons with an initial radius of 10-100 nm. The bubbles grew in an acoustic field at 19.3 kHz to a maximum size of 1 mm, then collapsed. D-D fusion leads to either production of helium and 2.5 MeV neutrons or tritium and protons.  Taleyarkhan claimed to have observed both excess 2.5 MeV neutrons and tritium.

Taleyarkhan presented background on triggering of metastable fluids at the Third International Conference on Transport Phenomena in Multiphase Systems (HEAT-2002), Kielce, Poland, June 24-27, 2002.
Nano-to-Macro Scale Triggering of Metastable Fluids
Rusi P. Taleyarkhan, Colin D. West and JaeSeon Cho
Abstract: Background information is provided on the controlling physics behind nano-to-macroscale explosive burst generation from pretensioned and/or superheated metastable liquids. Estimates of energetics from experimental evidence are provided where it is shown that relatively large energy outputs can be achieved. Conceptual schemes are discussed for inducing metastable states and for controlled triggering from neutrons, lasers and acoustic energy pulses.

Taleyarkhan's group presented their sonofusion results at a meeting of the Acoustical Society of America.
Evidence for nuclear emissions during neutron seeded acoustic bubble cavitation
Taleyarkhan, R. P.; West, C. D.; Cho, J. S.; Lahey, R. T., Jr.; Block, R. C.; Nigmatulin, R., The Journal of the Acoustical Society of America, vol. 112, iss. no. 5, p. 2269-2269
In cavitation experiments with deuterated acetone, statistically significant tritium decay activity above background levels was detected. In addition, evidence for statistically significant neutron emissions near 2.5 MeV was also observed, as would be expected for deuterium-deuterium fusion. Control experiments with normal acetone did not result in tritium activity or neutron emissions. Hydrodynamic shock code simulations supported the observed data and indicated compressed, hot (106-107 K) bubble implosion conditions, as required for thermonuclear fusion reactions. Separate experiments with additional fluids are under way and results appear to support those observed with acetone. Scalability potential to higher yields, as well as evidence for neutron-tritium branching ratios are presented.

Saltmarsh and Shapira commented on the Taleyarkhan's paper in Science.
Questions Regarding Nuclear Emissions in Cavitation Experiments, Science, 6 September 2002, M. J. Saltmarsh, Dan Shapira
Comments on the possible observation of dd fusion in sonoluminescence

Saltmarsh and Shapira then published a paper in Physical Review Letters based on results that they had obtained in June/July 2001 in an experiment using Taleyarkhan's apparatus, and his help. The experiment was done at the request of Oak Ridge National Laboratory to check the validity of a paper submitted unsuccessfully to Science earlier in 2001. Their results were negative, and were communicated to Taleyarkhan et al. in July 2001. Normally they would not have published a null result, but were asked to do so when ORNL discovered that the Science 2002 paper was to be published, with much of the data that had caused earlier concerns.

Nuclear fusion in collapsing bubbles-is it there? An attempt to repeat the observation of nuclear emissions from sonoluminescence. Shapira D, Saltmarsh M. Phys Rev Lett. 2002 Sep 2;89(10):104302.
We have repeated the experiment of Taleyarkhan et al. [Science 295, 1868 (2002)]] in an attempt to detect the emission of neutrons from d-d fusion during bubble collapse in deuterated acetone. Using the same cavitation apparatus, a more sophisticated data acquisition system, and a larger scintillator detector, we find no evidence for 2.5-MeV neutron emission correlated with sonoluminescence form collapsing bubbles. Any neutron emission that might occur is at least 4 orders of magnitude too small to explain the tritium production reported in Taleyarkhan et al. as being due to d-d fusion. We show that proper allowance for random coincidence rates in such experiments requires the simultaneous measurement of the count rates in the individual detectors.

The Taleyarkhan group replied to the critique in this letter, claiming that Shapira & Saltmarsh had in fact detected radiation from sonofusion. Comments on the Shapira/Saltmarsh Report

Here are Comments on "Evidence for Nuclear Emissions During Acoustic Cavitation" by R.P. Taleyarkhan et al., Science volume 295,p.1868, March 8, 2002. Authors: S.J. Putterman, L.A. Crum, K. Suslick.

Didenko and Suslick at the University of Illinois performed calculations to show that energy created during cavitation is dissipated by chemical processes, and hence sonofusion is unlikely.
The energy efficiency of formation of photons, radicals and ions during single-bubble cavitation.
Didenko YT, Suslick KS. Nature. 2002 Jul 25;418(6896):394-7.
It is extremely difficult to perform a quantitative analysis of the chemistry associated with multibubble cavitation: unknown parameters include the number of active bubbles, the acoustic pressure acting on each bubble and the bubble size distribution. Single-bubble sonoluminescence (characterized by the emission of picosecond flashes of light) results from nonlinear pulsations of an isolated vapour-gas bubble in an acoustic field. Although the latter offers a much simpler environment in which to study the chemical activity of cavitation, quantitative measurements have been hindered by the tiny amount of reacting gas within a single bubble (typically <10-13 mol). Here we demonstrate the existence of chemical reactions within a single cavitating bubble, and quantify the sources of energy dissipation during bubble collapse. We measure the yields of nitrite ions, hydroxyl radicals and photons. The energy efficiency of hydroxyl radical formation is comparable to that in multibubble cavitation, but the energy efficiency of light emission is much higher. The observed rate of nitrite formation is in good agreement with the calculated diffusion rate of nitrogen into the bubble. We note that the temperatures attained in single-bubble cavitation in liquids with significant vapour pressures will be substantially limited by the endothermic chemical reactions of the polyatomic species inside the collapsing bubble.

Geisler et al. could find no evidence of neutron emission from laser-induced cavitation bubbles in heavy water.
Search for neutron emission in laser-induced cavitation
R. Geisler, W.-D. Schmidt-Ott, T. Kurz and W. Lauterborn. Europhys. Lett., 66 (3) 435-440 (2004)
Abstract: Laser-induced cavitation bubbles in heavy water are investigated at different parameter settings. Neutrons are searched for in close temporal proximity to cavitation luminescence flashes with an estimated detection efficiency of 4%. No neutrons in coincidence with cavitation luminescence have been detected. This yields an upper limit of emitted neutrons per bubble collapse of 5 x 10-4.

Taleyarkhan's group presented updates and clarifications both on the theoretical framework and experimental conditions of their findings at a meeting of the Acoustical Society of America.

Update and clarifications on analytic studies for nuclear emissions during acoustic cavitation
Nigmatulin, Robert I.; Lahey, R. T.; Taleyarkhan, R. P.; West, C. D., Acoustical Society of America Journal, Volume 113, Issue 4, pp. 2205-2206 (2003).
A one-dimensional hydrodynamic shock (HYDRO) code was developed to numerically evaluate the conservation equations of each phase during bubble growth and collapse. This code includes the Mie-Gruniesen equations of state and Born-Mayer potential functions, which are known to be valid for highly compressed fluids. In particular, for acetone these equations of state are based on the shock wave adiabat data, and they implicitly specify the effect of the induced radiation field and the dissociation and ionization processes that take place during plasma formation within imploding bubbles. Moreover, relevant energy losses and the effect of both molecular and electron conductivity were taken into account, and the resultant HYDRO code allowed for the evaluation of shock wave interaction using the well-established Godunov numerical technique. Bubble dynamics were studied in deuterated acetone for conditions typical of those in our experiments. It was found that highly compressed conditions suitable for thermonuclear fusion were predicted, and the results were sensitive to the values of the phase change (that is, accommodation) coefficient, a, and the liquid pool temperature To.

Update and clarifications on experimental studies for nuclear emissions during acoustic cavitation
Authors: Taleyarkhan, Rusi P.; West, C. D.; Cho, J. S.; Lahey, R. T.; Block, R. C.; Nigmatulin, R. I.. Acoustical Society of America Journal, Volume 113, Issue 4, pp. 2223-2223 (2003).
A seminal discovery related to detection of nuclear emissions during acoustic inertial confinement fusion with deuterated acetone has been reported in Science (3/8/2002 issue). Nuclear emissions we measured included 2.5-MeV neutrons and tritium as would be expected from deuterium-deuterium nuclear fusion. These unmistakable statistically significant signatures were measured under conditions commensurate with degassed rapid condensation-induced implosion conditions only with the test fluid deuterated acetone. In these experiments bubble clusters are nucleated in tensioned degassed liquids with neutrons at the nanoscale level and are then made to grow by a factor of ~100,000 in size to the mm scale prior to implosive collapse. Similarly conducted control experiments with natural acetone did not result in any statistically significant nuclear emissions. Shock code simulations (discussed in a companion talk) corroborated these observations and provided insights into the physics of the overall process. Since the recent announcement of this discovery several world-wide researchers have contacted the authors for further clarifications in a variety of areas. The presentation will discuss these issues and questions, and will provide relevant explanations with supporting evidence.

Larry Crum has written a review of the ASA meeting on acoustic inertial confinement fusion, held in the summer of 2003.

Taleyarkhan's next major paper was published in Physical Review E. They replicated the sonofusion experiment with an upgraded measurement system.
Additional evidence of nuclear emissions during acoustic cavitation
Phys. Rev. E 69, 036109 (2004) (11 pages)
R. P. Taleyarkhan, J. S. Cho, C. D. West, R. T. Lahey, Jr., R. I. Nigmatulin, and R. C. Block
Abstract: Time spectra of neutron and sonoluminescence emissions were measured in cavitation experiments with chilled deuterated acetone. Statistically significant neutron and gamma ray emissions were measured with a calibrated liquid-scintillation detector, and sonoluminescence emissions were measured with a photomultiplier tube. The neutron emission energy corresponded to <2.5 MeV and had an emission rate of up to ~4 x 105 n/s. Measurements of tritium production were also performed and these data implied a neutron emission rate due to D-D fusion which agreed with what was measured. In contrast, control experiments using normal acetone did not result in statistically significant tritium activity, or neutron or gamma ray emissions.

A discussion of the mathematics involved is given in Bubble Fusion Hydro Code Analysis, a DARPA Talk given at Arlington, VA. June 19, 2003.

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.

A BBC program featured Seth Putterman trying to confirm Taleyarkhan's work.
BBC Horizon Programme, February 16, 2005 (full transcript)
Nuclear fusion from sound waves would be a huge scientific breakthrough. But to be convinced of it, many scientists wanted to see better evidence; evidence that was absolutely incontrovertible. They wanted to look very carefully at the timing of the neutrons to see just how closely they were related to the flashes of light. If they occurred at the exact same time, they would finally be convinced that fusion was taking place. The question was - just how exact did the measurements need to be?

The sceptics wanted to time it with incredible accuracy - that of a nanosecond, or a billionth of a second. This was one measurement that, though possible to do, still had not been carried out by Rusi Taleyarkhan and his team.

The BBC Horizon programme decided to try to sort out the issue once and for all. It commissioned an independent team led by Seth Putterman to conduct a unique experiment. Working from the instructions set out in Rusi Taleyarkhan's paper, it assembled the same key scientific conditions necessary to create nuclear fusion from sonoluminescence. But to see if it could find fusion, we measured the neutrons and the flashes of light simultaneously with nanosecond accuracy, something that had never been done before.

Recording data nanosecond by nanosecond, Seth Putterman did not find a single neutron close enough to a flash of light for it to be considered the result of nuclear fusion. So the conclusion was negative. Horizon put this conclusion to Rusi Taleyarkhan who said that several differences in the equipment could have made affected the results.

According to Mike Saltmarsh, Seth Putterman found no neutrons above background, implying any fusion events were at least a factor of 100,000 less than that claimed by Taleyarkhan.,

Sonofusion - Fact or Fiction? By Richard T Lahey, Jr., Rusi P Taleyarkhan and Robert I Nigmatulin. To be presented at the 11th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics (NURETH-11), Popes' Palace Conference Center, Avignon, France, October 2-6, 2005. Only 7 orders of magnitude to break-even.

Flanigan and Suslick reported that collapsing bubbles of argon in sulfuric acid have a hot plasma core. Suslick said "Our results can neither confirm or deny Taleyarkhan's claims to fusion". But he adds that any confined fusion reaction requires a plasma. "Our paper shows for the first time, and definitively, that there can be a plasma formed during this process." Proof of the plasma comes from the presence of an ionic oxygen molecule (O2+). Some process must remove an electron from the molecule without breaking the chemical bond holding the two atoms together. Heating alone would break the molecule in two, so Suslick and Flannigan argue that the molecule was ionized after it collided with high-energy electrons or other ions in a hot plasma core. The temperature measured of the optically opaque plasma surface - about 20,000 K - is four times hotter than the surface of the sun. The core of the collapsing bubble must be even hotter than the surface.

Plasma formation and temperature measurement during single-bubble cavitation. Flannigan D. J. & Suslick K. S. Nature 434, 52 - 55 (2005).
Single-bubble sonoluminescence (SBSL) results from the extreme temperatures and pressures achieved during bubble compression; calculations have predicted the existence of a hot, optically opaque plasma core with consequent bremsstrahlung radiation. Recent controversial reports claim the observation of neutrons from deuterium–deuterium fusion during acoustic cavitation. However, there has been previously no strong experimental evidence for the existence of a plasma during single- or multi-bubble sonoluminescence. SBSL typically produces featureless emission spectra that reveal little about the intra-cavity physical conditions or chemical processes. Here we report observations of atomic (Ar) emission and extensive molecular (SO) and ionic (O2+) progressions in SBSL spectra from concentrated aqueous H2SO4 solutions. Both the Ar and SO emission permit spectroscopic temperature determinations, as accomplished for multi-bubble sonoluminescence with other emitters. The emissive excited states observed from both Ar and O2+ are inconsistent with any thermal process. The Ar excited states involved are extremely high in energy (>13 eV) and cannot be thermally populated at the measured Ar emission temperatures (4,000-15,000 K); the ionization energy of O2 is more than twice its bond dissociation energy, so O2+ likewise cannot be thermally produced. We therefore conclude that these emitting species must originate from collisions with high-energy electrons, ions or particles from a hot plasma core.

In the May 2005 issue of IEEE Spectrum, Taleyarkhan et al. presented more evidence for sonofusion and discuss the possibility of scaling the phenomenon into an electricity-generating device. They claim that "at least five groups--three in the United States and two in Europe--are working on reproducing our sonofusion results. Some have apparently already succeeded and are now preparing to publish their findings."

In 2005, Yiban Xu and Adam Butt at Purdue University published the first "independent" confirmation of Taleyarkhan's work. Xu and Butt copied Taleyarkhan's setup, except that instead of using a precise time-based nucleation pulse neutron generator, they used a continuous isotope neutron source.

Confirmatory experiments for nuclear emissions during acoustic cavitation
Yiban Xua and Adam Butt. Nuclear Engineering and Design 235 (2005) 1317-1324.
Confirmatory experiments were conducted to assess the potential for nuclear fusion related emissions of neutrons and tritium during neutron-seeded acoustic cavitation of deuterated acetone. Corresponding control experiments were conducted with normal acetone. Statistically significant (5-11 S.D. increased) emissions of 2.45 MeV neutrons and tritium were measured during cavitation experiments with chilled deuterated acetone. Control experiments with normal acetone and irradiation alone did not result in tritium activity or neutron emissions. Insights from imaging studies of bubble clusters and shock trace signals relating to bubble nuclear fusion are discussed.

Xu, Butt and Shripad Revankar plan to present their findings at the 11th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics (NURETH-11) in October 2005.

In early 2006, Taleyarkhan published an article in Phys Rev Lett, this time changing his method of inducing bubble formation. Instead of using an external source of neutrons, he used a mixture of deuterated acetone and benzene with a uranium salt. As the uranium undergoes radioactive decay it releases alpha particles, which seed the bubble formation. They used three independent neutron detectors and a gamma-ray detector to monitor the sonofusion. Although uranium can release neutrons during fission reactions, Taleyarkhan ruled them out because the neutrons he finds bear the energetic hallmark of having come from the fusion of two deuterium nuclei. Taleyarkhan admitted that the experiment doesn't always work, and the group is not sure why.  Tritium could not be detected in this experiment because its signature is overwhelmed by an interfering signal from uranium decay.
 
Phys. Rev. Lett. 96, 034301 (2006) Nuclear Emissions During Self-Nucleated Acoustic Cavitation. R. P. Taleyarkhan, C. D. West, R. T. Lahey, Jr., R. I. Nigmatulin, R. C. Block and Y. Xu

A unique, new stand-alone acoustic inertial confinement nuclear fusion test device was successfully tested. Experiments using four different liquid types were conducted in which bubbles were self-nucleated without the use of external neutrons. Four independent detection systems were used (i.e., a neutron track plastic detector to provide unambiguous visible records for fast neutrons, a BF3 detector, a NE-113-type liquid scintillation detector, and a NaI γ-ray detector). Statistically significant nuclear emissions were observed for deuterated benzene and acetone mixtures but not for heavy water. The measured neutron energy was <2.45 MeV, which is indicative of deuterium-deuterium (D-D) fusion. Neutron emission rates were in the range ~5×103 n/s to ~104 n/s and followed the inverse law dependence with distance. Control experiments did not result in statistically significant neutron or γ-ray emissions.

In March 2006 Purdue University opened an investigation into "extremely serious" concerns regarding Taleyarkhan's research. This is usually not a good thing. Brian Naranjo, a graduate student in Seth Putterman's lab at UCLA said his analysis of data from the last scientific paper that was published by Dr. Taleyarkhan's group showed a chance of less than one in 10 million that the emission pattern could have been generated by fusion. The pattern of particles seen in the experiment much more closely matched that given off by californium, a radioactive element that is used in Dr. Taleyarkhan's laboratory.  To disprove this contention, Taleyarkhan intentionally exposed his device to a Californium-252 source and showed that the resulting spectra were different than those in his earlier publications.

Purdue faculty members Lefteri Tsoukalas and Tatjana Jevremovic say that they seriously doubt the reality of the bubble-fusion effect. Since his arrival at the university, they say, Taleyarkhan has declined to share the raw data he claims to have obtained in successful experiments on shared equipment. The faculty members add that he has opposed publication of their own negative results and has removed the equipment on which they were trying to replicate his work.

Purdue University completed their review in June, 2006, but declined to elaborate on their findings. "Any further action in this matter will be conducted as an internal matter under appropriate university procedures."

In February 2007, Purdue University announced that an internal inquiry had cleared Taleyarkhan of allegations of research misconduct.  The Purdue committee conducting the inquiry said in a statement "that the evidence does not support the allegations of research misconduct and that no further investigation of the allegations is warranted." However, Purdue released no details of the inquiry and said it would not publish the report. Seth Putterman was displeased with this investigation because Purdue did not interview critics outside the university nor did they appoint external members to the review committee.

In March 2007, the Purdue University investigation of Taleyarkan became the subject of a Congressional inquiry. Based on criticism from Congress, Purdue decided in May to conduct another investigation. This time the focus of the investigation will not be on whether Taleyarkhan improperly omitted himself as an author on two scientific papers, but whether the underlying research might have been fraudulent.

In March 2008, Taleyarkhan filed a lawsuit for defamation, civil harassment and intentional inflection of emotional against Lefteri Tsoukalas and Tatjana Jevremovic. Taleyarkhan claimed that Tsoukalas discriminated against him because of his Indian ethnicity.

In April 2008, Purdue University turned over the results of their investigation of research misconduct allegations to the Office of Naval Research. Purdue would not comment on the investigation until the ONR responded.

In July 2008,  the Purdue University panel announced that Taleyarkhan had violated research ethics. The committee concluded that Taleyarkhan falsely claimed independent confirmation of his experiment results. The panel also found that he added another person as an author of research, even though the person did not substantially contribute to the publication. The university committee denied an appeal by Taleyarkhan and took away his named professorship because of the research misconduct. Taleyarkhan was allowed to remain a member of the university's faculty but was not allowed to serve as a major professor for graduate students for at least three years.

Taleyarkhan published again in Nuclear Engineering and Design, refuting Naranjo's finding, explaining that ice-pack shielding between the detector and the fusion neutron source, gamma photon leakage and neutron pulse-pileup due to picosecond duration neutron pulse emission effects play important roles in affecting the spectra of neutrons from acoustic inertial confinement thermonuclear fusion experiments.
Taleyarkhan, R.P., J. Lapinskas, Y. Xu, J. S. Cho, R. C. Block, R. T. Lahey, Jr., and R. I. Nigmatulin. Modeling, analysis and prediction of neutron emission spectra from acoustic cavitation bubble fusion experiments. Nucl. Eng. Des. (2008) 2779-2791.

Taleyarkhan filed a suit against two Purdue faculty members, Lefteri Tsoukalas and Tatjana Jevremovc, claiming they made false and malicious statements that damaged his career in sonofusion research.

Patents & Commercial Efforts (since the Taleyarkhan paper)

Taleyarkhan has filed patent applications for a sonofusion energy device.
WO 02/097823, 24 May 2002, Methods and Apparatus to Induce D-D amd D-T Reactions (see also US 2005 0135532 A1)
Rusi P Taleyarkhan, Colin D West
A nuclear fusion reactor includes a structure for placing at least a portion of a liquid into a tension state, the tension state being below a cavitation threshold of the liquid. The tension state imparts stored energy into the liquid portion. A cavitation initiation source provides energy to the liquid portion sufficient to nucleate at least one bubble having a bubble radius greater than a critical bubble radius of the liquid. A structure for imploding the bubbles produces imploded cavities. The temperature generated by the implosion process can be sufficient to induce a nuclear fusion reaction involving the liquid. A method for providing nuclear fusion tensions a liquid, cavitates the tensioned liquid to form at least one bubble, then implodes the bubble, wherein a resulting temperature is generated that is sufficent to induce a nuclear fusion reaction involving the liquid.

Nanoscale explosive-implosive burst generators using nuclear-mechanical triggering of pretensioned liquids
US Patent Application 20030074010, Taleyarkhan, Rusi P. April 17, 2003
A burst generator includes a structure for placing at least a portion of a liquid into a tension state, the tension state being below a cavitation threshold of the liquid. The tension state imparts stored mechanical energy into the liquid portion. A structure for cavitating provides energy to the liquid portion sufficient to bubble nucleate at least one bubble having a bubble radius greater than a critical bubble radius of the liquid, formation of the bubble releasing at least a portion of the energy which is stored in the tension state.

Impulse Devices Inc. is a company interested in developing sonofusion devices. Their lead technologist appears to be Ross Tessien, who has filed a dozen patent applications for cavitation nuclear reactors. Impulse Devices has funded research by ANSR (Adaptive Network Solutions Research, Inc) to study sonofusion.

WO0139201C2: Nouveau systeme perfectionne pour la suppression de la chaleur dans un reacteur nucleaire a cavitation. Cavitation nuclear reactor cooling system includes heat transfer circuit and driver refrigeration circuit. Inventor: Ross Tessien. Assignee: Impulse Devices, Inc. Filed: 2000-11-20, Published: 2003-01-30.
Abstract: Cavitation nuclear reactors generally have a reaction chamber within which the cavitation nuclear reactions take place. Cavitation nuclear reactions are driven by acoustic energy. In order to generate the necessary acoustic energy, drivers are connected to the reaction chamber. This new and improved system utilizes two independent circuits to increase the efficiency of the cavitationn nuclear reactors. One circuit serves to remove the energy from the interior of the reaction chamber at as high a temperature as possible. The other circuit acts to cool downs the drivers so as to allow the drivers to operate within the optimal operating temperature range.

On December 13, 2004 Impulse Devices Inc. announced the availability of its research reactor to laboratories, universities, power equipment manufacturers and utilities attempting to produce a new alternative energy. Using proprietary technology, the IDI reactor is a stainless steel sphere filled with heavy water and, at its center, a small bubble of deuterium (heavy hydrogen). Sound waves cause the bubble, first to expand greatly, followed by its collapse to a fraction of its original size, all at the rate of thousands of times a second. This produces enormous temperatures that, when high enough, fuse the heavy hydrogen into helium, releasing heat that could be used to create steam and drive a turbine to produce electricity. Single-bubble, acoustic inertial confinement was first discovered in 1989, by Dr. D. Felipe Gaitan, now Chief Scientist at IDI. The IDI research reactor has a diameter of 1 foot and costs $250,000 with custom input-output systems and instrumentation. IDI and several universities and laboratories are forming the Acoustic Fusion Technology Energy Consortium (AFTEC), to research and develop AICF (acoustic inertial confinement fusion )and related technologies and equipment.

Another application from Impulse Devices: US20060018420A1: Heat exchange system for a cavitation chamber  Inventor:
Tessien, Ross Alan; Nevada City, CA. Published / Filed: 2006-01-26 / 2004-10-25

In July 2005, Impulse Devices purchased a pulsed neutron generator made by Thermo Electron Corporation for $80,000.

Another company working on fusion devices, mostly solid state, is D2Fusion. Their lead technologist is Russ George, who has been studying sonofusion since at least 1997. Russ George is also involved in Saturna Technologies, Inc.

A Canadian company, General Fusion Inc., has filed the following patent application.
WO 03/077260, 12 March 2003, Apparatus and Method for Fusion Reactor
Michel Laberge, Gavin N Manning
A method for inducing nuclear fusion and a reactor for inducing nuclear fusion involve positioning a bubble containing fusionable nuclei at the center of a liquid filled spherical vessel and generating a spherically symmetric positive acoustic pulse in the liquid. The acoustic pulse surrounds and converges toward the center of the vessel to compress the bubble, thereby providing energy to and inducing nuclear fusion of the atomic nuclei.

Arthur Enfinger has filed an application for an acoustic wave nuclear reactor. His association is unknown.
US20040141578A1: Nuclear fusion reactor and method
Inventor: Enfinger, Arthur L.; Pensacola, FL, United States of America
Published / Filed: 2004-07-22 / 2003-01-16
Abstract: A nuclear fusion reactor comprising a spherical reaction chamber with a mirrored interior surface filled with a nuclear fusible and laser active gaseous medium such as deuterium. Using rapid gaseous expansion caused by a focused pulsed laser source and/or timed oscillations from piezoelectric transducer, a harmonic spherical acoustic wave pattern centered within the reaction chamber is created. This wave pattern is created near a desired frequency and centered in the sphere. The wave pattern contains a central gaseous ball of high-density, pressure, and temperature that causes ionization and radiation to occur. This radiation causes the mirrored chamber to activate a spherical laser effect focused on the high pressure plasma at the center of the reaction chamber. This spherical laser pulse acting on high pressure high-density of the central standing wave produces ignition of the gas and fusion. The tremendous energy from fusion drives the acoustic process which ideally allows for a self sustaining ignition temperature plasma requiring the addition of fuel only.

American Technologies Group produced car care products and dabbles in high energy particle physics. Shui-Yin Lo has a cavitation fusion patent application from 1997.
WO9749274A2: A method for generating nuclear fusion through high pressure.
Title: Changing structure of material - comprises forming bubbles in liquid inside chamber, expanding bubbles, reducing volume of bubbles, adding heat energy and further reducing volume.
Inventor: Shui-Yin Lo
Assignee: American Technologies Group, Inc., 1017 S. Mountain Avenue, Monrovia, CA 91016,
Published / Filed: 1997-12-31 / 1997-06-11
Abstract: A method of generating nuclear fusion, whereby bubbles of a gas of about 10 micron diameter, contained in heavy water, are expanded by use of a vacuum to about 100 microns in diameter. The subsequent thermal cooling and collapse of the bubbles is augmented by a uniform pressure externally applied and acting on the bubbles through the heavy water. Symmetry in the bubbles' shape is imparted by the addition of heat from a laser as the bubbles continue to contract. High pressures and therefore temperatures are achieved, sufficient to generate nuclear fusion in specific materials.

A fringe researcher in the area is Roger Stringham of First Gate Energies, who has presented several posters at the International Conferences on Cold Fusion. See his abstract for a March 2003 presentation entitled Sonofusion: Heat and 4He Created by Cavitationally Induced Loading of Metal Foils, and his patent application US20020090047A1: Apparatus for producing ecologically clean energy.

WO/2008/013571.   Acoustic Inertial Confinement Nuclear Device. Taleyarkhnan,  Rusi, P.
An acoustic inertial confinement nuclear fusion device is disclosed. The device includes an enclosure that holds a fluid with dissolved alpha emitters. A generator is coupled to the enclosure, and the generator is configured to harmonically drive the fluid in the enclosure to induce an acoustic standing wave in the fluid. The dissolved alpha emitters nucleate bubble clusters in the fluid as the fluid is driven by the generator. Neutrons, tritium and/or gamma rays, are emitted from the fluid, without or with an external source of neutrons.

Sonofusion Calculations

On this page I've set up some simple Javascript calculations to let you estimate the parameters of sonofusion processes.

Other Links

Wikipedia Article on Sonoluminescence
Scientific American Article by Seth Putterman
Wikipedia Article on Bubble Fusion
DARPA Sonofusion Project
Ludwik Kowalski has many interesting essays on cold fusion.
Infinite Energy is a magazine on fusion and alternative energies.
Cold Fusion Times is another magazine chronicling events in the area.
New Energy Times is yet another.
ZP Energy
Pyroelectric Crystal Fusion

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