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U. of I. study casts doubt on bubble fusion report
http://www.chicagotribune.com/news/nationworld/chi-0207250403jul25.story
U. of I. study casts doubt on bubble fusion report
By Jeremy Manier
Tribune staff reporter
July 25, 2002
Studying tiny water bubbles that collapse in intense flashes of light
and heat, scientists at the University of Illinois at Urbana-Champaign
have added a skeptical note to a growing controversy over whether
similar bubbles could create cheap energy through nuclear fusion.
The Illinois team's work, published Thursday in the journal Nature, may
cast more doubt on a disputed report from earlier this year in which
physicists at Oak Ridge National Laboratory in Oak Ridge, Tenn., said
they had detected fusion reactions in bubble experiments. Some
researchers criticized the work as inconclusive, recalling a furor in
the 1980s over unfounded claims that scientists had discovered the key
to limitless energy using "cold fusion."
Nuclear fusion, the potent energy source that powers the sun and
hydrogen bombs, has been produced in a controlled way only in vast and
expensive
experimental facilities. The instruments used achieve fusion by
subjecting a form of hydrogen to intense heat and pressure, causing the
atoms to fuse.
If successful, bubble fusion could replicate that process in devices
that fit on a tabletop, possibly providing a cheap and clean source of
energy.
In contrast to the cold fusion debacle, the concept of bubble fusion is
at least theoretically plausible, experts say. The technique consists of
bombarding a small container of liquid with powerful sound waves,
causing gas bubbles in the fluid to implode violently.
Even if the Oak Ridge team did not detect fusion reactions, other groups
are attempting the feat, and experts say one of those teams may succeed
soon.
If anyone could prove that bubble fusion works, "It would be one of the
most important discoveries of the century," said Lawrence Crum, a
physicist at the
Applied Physics Lab of the University of Washington at Seattle. Though
doubtful of the Oak Ridge team's findings, Crum said he has seen
promising
unpublished results from other researchers.
The U. of I. team's study suggests that such efforts may face daunting
obstacles. Measuring the reactions that occur when a gas bubble inside a
water container is blasted with ultrasound, Illinois chemistry professor
Kenneth Suslick found that much of the energy needed for fusion is used
up in small-scale chemical reactions.
Still, Suslick said, "The concept of getting fusion this way is not in
any way crackpot--as opposed to cold fusion, which had no underlying
basis at all."
The potential for a new source of fusion is attracting attention for an
obscure branch of science devoted to the study of energetic little
bubbles. For more than 60 years, physicists have known that when bubbles
in a liquid are excited by intense sound waves, they can expand and then
suddenly collapse in flashes of light.
Similar but less intense bubble implosions are what make the sound of a
boat propeller or a babbling brook.
Researchers still do not know precisely how the energy in sound waves
becomes focused enough in the collapsing bubbles to emit light. A 1994
paper by
researchers at the University of California at Los Angeles was the first
to propose that an intense bubble collapse, creating temperatures of
thousands or even millions of degrees, could result in nuclear fusion.
Experts say the Illinois team's new study shows how the heat in a single
compressed bubble is converted into light, chemical reactions and other
forms of energy. Although Suslick's method could not be used to attempt
fusion, he said the work suggests that nuclear fusion would be difficult
to achieve because chemical reactions "eat up all the energy in the
bubble."
Most researchers say the real test of bubble fusion will come in
experiments using far more powerful acoustic energies.
Scientists at Oak Ridge still believe they detected fusion during a
bubble experiment published in March in the journal Science. While
directing ultrasound at a vessel containing liquid acetone and a form of
hydrogen, the researchers found emissions of neutrons--a byproduct of
nuclear fusion.
"We're absolutely sure," said Dick Lahey, a co-author on the Oak Ridge
study and a professor of engineering at Rensselaer Polytechnic
Institute, in Troy, N.Y.
But other experts saw serious flaws in the team's experimental
techniques. For example, neutron readings did not always occur at the
same time as the bubble flashes, said Seth Putterman, a UCLA physics
professor and co-author of the 1994 paper outlining bubble fusion.
Such flaws led Putterman, Crum and Suslick, who were official reviewers
for the journal Science, to conclude that the study was not ready for
publication. Putterman said he is still puzzled as to how that first
claim of bubble fusion passed peer review. "I'm lost," he said. "I don't
know anyone who backs those findings."
Even if successful, the scale of bubble fusion would be extremely small.
In most experiments to date, even the biggest bubbles are barely
visible.
"To someone who's interested in new sources for power stations, it would
be very boring," Putterman said. "We haven't let ourselves think of that
next step."
Copyright © 2002, Chicago Tribune
--
.....................................................
Susan L. Gawarecki, Ph.D., Executive Director
Oak Ridge Reservation Local Oversight Committee
102 Robertsville Road, Suite B, Oak Ridge, TN 37830
Toll free 888-770-3073 ~ www.local-oversight.org
.....................................................
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