[extropy-chat] sonofusion tested on BBC tonight

[Damien Broderick]

The BBC is showing a program tonight on cold fusion claims (of a sort). If 
anyone here watches it, maybe they could report back?

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Horizon
Thu 17 Feb, 9:00 pm - 9:50 pm  50mins

An Experiment to Save the World

Horizon takes one of the most controversial and ambitious claims in 
science, and conducts an experiment to see if it's really true. If the 
experiment works, then the world could be on the way to a new form of 
cheap, unlimited, pollution free energy. But if it fails, then that dream 
will die. The experiment is an attempt to make nuclear fusion, one of the 
Holy Grails of science. [etc]

=============
[here's a piece from last year on Rusi Taleyarkhan's work, from 
http://www.spacedaily.com/news/energy-tech-04o.html ]

Evidence Bubbles Over To Support Tabletop Nuclear Fusion Device

Rusi Taleyarkhan, an Oak Ridge National Laboratory scientist is part of a 
group working towards the dream of sustained fusion energy.
West Lafayette - Mar 04, 2004
Researchers are reporting new evidence supporting their earlier discovery 
of an inexpensive "tabletop" device that uses sound waves to produce 
nuclear fusion reactions.

The researchers believe the new evidence shows that "sonofusion" generates 
nuclear reactions by creating tiny bubbles that implode with tremendous 
force. Nuclear fusion reactors have historically required large, 
multibillion-dollar machines, but sonofusion devices might be built for a 
fraction of that cost.

"What we are doing, in effect, is producing nuclear emissions in a simple 
desktop apparatus," said Rusi Taleyarkhan, the principal investigator and a 
professor of nuclear engineering at Purdue University. "That really is the 
magnitude of the discovery – the ability to use simple mechanical force for 
the first time in history to initiate conditions comparable to the interior 
of stars."

The technology might one day, in theory, lead to a new source of clean energy.

It may result in a new class of low-cost, compact detectors for security 
applications that use neutrons to probe the contents of suitcases; devices 
for research that use neutrons to analyze the molecular structures of 
materials; machines that cheaply manufacture new synthetic materials and 
efficiently produce tritium, which is used for numerous applications 
ranging from medical imaging to watch dials; and a new technique to study 
various phenomena in cosmology, including the workings of neutron stars and 
black holes.

Taleyarkhan led the research team while he was a full-time scientist at the 
Oak Ridge National Laboratory, and he is now the Arden L. Bement Jr. 
Professor of Nuclear Engineering at Purdue.

The new findings are being reported in a paper that will appear this month 
in the journal Physical Review E, published by the American Physical 
Society. The paper was written by Taleyarkhan; postdoctoral fellow J.S Cho 
at Oak Ridge Associated Universities; Colin West, a retired scientist from 
Oak Ridge; Richard T. Lahey Jr., the Edward E. Hood Professor of 
Engineering at Rensselaer Polytechnic Institute (RPI); R.C. Nigmatulin, a 
visiting scholar at RPI and president of the Russian Academy of Sciences' 
Bashkortonstan branch; and Robert C. Block, active professor emeritus in 
the School of Engineering at RPI and director of RPI's Gaerttner Linear 
Accelerator Laboratory.

The discovery was first reported in March 2002 in the journal Science.

Since then the researchers have acquired additional funding from the U.S. 
Defense Advanced Research Projects Agency, purchased more precise 
instruments and equipment to collect more accurate data, and successfully 
reproduced and improved upon the original experiment, Taleyarkhan said.

"A fair amount of very substantial new work was conducted, " Taleyarkhan 
said. "And also, this time around I made a conscious decision to involve as 
many individuals as possible – top scientists and physicists from around 
the world and experts in neutron science – to come to the lab and review 
our procedures and findings before we even submitted the manuscript to a 
journal for its own independent peer review."

The device is a clear glass canister about the height of two coffee mugs 
stacked on top of one another. Inside the canister is a liquid called 
deuterated acetone. The acetone contains a form of hydrogen called 
deuterium, or heavy hydrogen, which contains one proton and one neutron in 
its nucleus. Normal hydrogen contains only one proton in its nucleus.

The researchers expose the clear canister of liquid to pulses of neutrons 
every five milliseconds, or thousandths of a second, causing tiny cavities 
to form. At the same time, the liquid is bombarded with a specific 
frequency of ultrasound, which causes the cavities to form into bubbles 
that are about 60 nanometers – or billionths of a meter – in diameter. The 
bubbles then expand to a much larger size, about 6,000 microns, or 
millionths of a meter – large enough to be seen with the unaided eye.

"The process is analogous to stretching a slingshot from Earth to the 
nearest star, our sun, thereby building up a huge amount of energy when 
released," Taleyarkhan said.

Within nanoseconds these large bubbles contract with tremendous force, 
returning to roughly their original size, and release flashes of light in a 
well-known phenomenon known as sonoluminescence. Because the bubbles grow 
to such a relatively large size before they implode, their contraction 
causes extreme temperatures and pressures comparable to those found in the 
interiors of stars. Researches estimate that temperatures inside the 
imploding bubbles reach 10 million degrees Celsius and pressures comparable 
to 1,000 million earth atmospheres at sea level.

At that point, deuterium atoms fuse together, the same way hydrogen atoms 
fuse in stars, releasing neutrons and energy in the process. The process 
also releases a type of radiation called gamma rays and a radioactive 
material called tritium, all of which have been recorded and measured by 
the team. In future versions of the experiment, the tritium produced might 
then be used as a fuel to drive energy-producing reactions in which it 
fuses with deuterium.

Whereas conventional nuclear fission reactors produce waste products that 
take thousands of years to decay, the waste products from fusion plants are 
short-lived, decaying to non-dangerous levels in a decade or two.

The desktop experiment is safe because, although the reactions generate 
extremely high pressures and temperatures, those extreme conditions exist 
only in small regions of the liquid in the container – within the 
collapsing bubbles.

One key to the process is the large difference between the original size of 
the bubbles and their expanded size. Going from 60 nanometers to 6,000 
microns is about 100,000 times larger, compared to the bubbles usually 
formed in sonoluminescence, which grow only about 10 times larger before 
they implode.

"This means you've got about a trillion times more energy potentially 
available for compression of the bubbles than you do with conventional 
sonoluminescence," Taleyarkhan said. "When the light flashes are emitted, 
it's getting extremely hot, and if your liquid has deuterium atoms compared 
to ordinary hydrogen atoms, the conditions are hot enough to produce 
nuclear fusion."

The ultrasound switches on and off about 20,000 times a second as the 
liquid is being bombarded by neutrons.

The researchers compared their results using normal acetone and deuterated 
acetone, showing no evidence of fusion in the former.

Each five-millisecond pulse of neutrons is followed by a five-millisecond 
gap, during which time the bubbles implode, release light and emit a surge 
of about 1 million neutrons per second.

In the first experiments, with the less sophisticated equipment, the team 
was only able to collect data during a small portion of the 
five-millisecond intervals between neutron pulses. The new equipment 
enabled the researchers to see what was happening over the entire course of 
the experiment.

The data clearly show surges in neutrons emitted in precise timing with the 
light flashes, meaning the neutron emissions are produced by the collapsing 
bubbles responsible for the flashes of light, Taleyarkhan said.

"We see neutrons being emitted each time the bubble is imploding with 
sufficient violence," Taleyarkhan said.

Fusion of deuterium atoms emits neutrons that fall within a specific energy 
range of 2.5 mega-electron volts or below, which was the level of energy 
seen in neutrons produced in the experiment. The production of tritium also 
can only be attributed to fusion, and it was never observed in any of the 
control experiments in which normal acetone was used, he said.

Whereas data from the previous experiment had roughly a one in 100 chance 
of being attributed to some phenomena other than nuclear fusion, the new, 
more precise results represent more like a one in a trillion chance of 
being wrong, Taleyarkhan said.

"There is only one way to produce tritium – through nuclear processes," he 
said.

The results also agree with mathematical theory and modeling.

Future work will focus on studying ways to scale up the device, which is 
needed before it could be used in practical applications, and creating 
portable devices that operate without the need for the expensive equipment 
now used to bombard the canister with pulses of neutrons.

"That takes it to the next level because then it's a standalone generator," 
Taleyarkhan said. "These will be little nuclear reactors by themselves that 
are producing neutrons and energy."

Such an advance could lead to the development of extremely accurate 
portable detectors that use neutrons for a wide variety of applications.

"If you have a neutron source you can detect virtually anything because 
neutrons interact with atomic nuclei in such a way that each material shows 
a clear-cut signature," Taleyarkhan said.

The technique also might be used to synthesize materials inexpensively.

"For example, carbon is turned into diamond using extreme heat and 
temperature over many years," Taleyarkhan said. "You wouldn't have to wait 
years to convert carbon to diamond. In chemistry, most reactions grow 
exponentially with temperature. Now we might have a way to synthesize 
certain chemicals that were otherwise difficult to do economically.

"Several applications in the field of medicine also appear feasible, such 
as tumor treatment."

Before such a system could be used as a new energy source, however, 
researchers must reach beyond the "break-even" point, in which more energy 
is released from the reaction than the amount of energy it takes to drive 
the reaction.

"We are not yet at break-even," Taleyarkhan said. "That would be the 
ultimate. I don't know if it will ever happen, but we are hopeful that it 
will and don't see any clear reason why not. In the future we will attempt 
to scale up this system and see how far we can go."