[extropy-chat] Cold Fusion: Honest!

[Terry W. Colvin]

  Cold fusion

Honest!
Apr 28th 2005
 >From The Economist print edition






A report of a desktop experiment that produces nuclear fusion is bound 
to raise eyebrows. But this time, the results look convincing

PHYSICISTS who meddle with cold fusion, like psychologists who dabble in 
the paranormal, are likely to be labelled quacks by their peers. This is 
due to an infamous incident in 1989 when Stanley Pons and Martin 
Fleischmann held a press conference to announce their discovery of 
nuclear fusion in what amounted to a test-tube full of water connected 
to a battery. In particular, they said that they were getting more 
energy out of the process than they put into it. Their result was 
instantly dubbed "cold fusion", to contrast it with giant fusion-reactor 
experiments that attempt to reproduce the ultra-high temperatures found 
inside the sun. But when it failed to stand up to scrutiny, 
confusion--and eventually outrage--ensued.

In 2002, history repeated itself as farce with the announcement by a 
group at Oak Ridge National Laboratory in Tennessee of fusion inside the 
bubbles that are produced by ultrasonic waves travelling through a 
liquid. This result passed the peer-review process, but was immediately 
attacked by another group--from the same laboratory--which claimed to 
find no such effect. There was a counterclaim by yet a third team last 
year, and a final verdict on "bubble fusion" is still not in. But most 
people have lost interest in the debate, assuming that anyone claiming 
to have observed fusion in a desktop experiment is a crank or a fraud. 
This attitude, however, may yet turn out to be mistaken. Desk-top fusion 
may be possible after all, according to an article published in this 
week's Nature by three researchers at the University of California, Los 
Angeles (UCLA).


Brian Naranjo, Jim Gimzewski and Seth Putterman have been meticulous in 
their experiment, and in particular in their measurement of one of the 
tell-tales of nuclear fusion, the production of neutrons. Their results 
have been peer-reviewed, and they make no wild claims of surplus energy 
being produced. Given past excesses, such caution is understandable. And 
it may indeed be the case that their technique, which involves banging 
together the nuclei of deuterium atoms (a heavy form of hydrogen) using 
a tiny crystal in a palm-sized vacuum chamber, will never provide a 
source of power. It could have some interesting applications, nonetheless.


Energy from crystals

In principle, nuclear fusion is a simple process. All you have to do is 
push two suitable atomic nuclei close enough together for them to 
overcome their mutual electrical repulsion (since both are positively 
charged) and they will merge. This merger releases oodles of energy. The 
usual way to push nuclei together is to smash them into one another at 
high speed. In thermonuclear fusion (the sort that happens in the sun, 
in hydrogen bombs, and in traditional fusion experiments) that speed is 
achieved by heating the atoms up. But this, as Dr Naranjo and his 
colleagues realised, is not the only way to do things. You can, as they 
have done, simply accelerate a stream of nuclei to high velocity, and 
fire them into a stationary target.

Traditional accelerators, such as those used in particle-physics 
experiments, use high-voltage electricity to achieve this acceleration. 
However, they are cumbersome and they consume a lot of power while doing 
so. Dr Naranjo, by contrast, has devised a compact way of generating 
high voltages at much lower power using a so-called pyroelectric crystal.

Heating such a crystal (or, rather, warming it from -30°C to just above 
freezing point) deforms its structure in a way that concentrates 
positive charge in one place and negative charge in another. That 
results in a big voltage between the two. The researchers then amplified 
the effect of the positive charge by attaching a metal tip to the place 
where it was accumulating. This concentrated the electrical field in the 
same way that the point of a lightning conductor concentrates the stroke.

Dr Naranjo used this effect two ways: first to strip deuterium atoms of 
their electrons and second to repel the resulting stream of deuterium 
nuclei at high speed towards a target containing more deuterium. When 
two deuterium nuclei (each composed of a proton and a neutron) fuse, the 
result is a type of helium composed of two protons and a neutron, a free 
neutron, and a lot of energy. The bombardment also produces a lot of 
X-rays. By counting the neutrons and measuring the X-rays the 
researchers estimate that about 1,000 pairs of deuterium nuclei were 
fusing every second.

This is, as they are the first to admit, a long way from producing a 
significant amount of energy. And although they reckon they could boost 
the fusion rate 1,000-fold with better apparatus, that still might not 
reach the magic threshold of producing more energy than it takes to run 
the experiment. Beyond that, they are understandably unwilling to speculate.

This does not, however, mean that their device will have no 
applications. With only a little tweaking it could be turned into a 
handheld X-ray scanner, which would be a significant medical advance. 
Not yet a precursor to a starship engine, perhaps, but maybe an ancestor 
of Dr McCoy's portable diagnosis machine.

< http://www.economist.com/displaystory.cfm?story_id=3909490 >



-- 
"Only a zit on the wart on the heinie of progress." Copyright 1992, Frank Rice


Terry W. Colvin, Sierra Vista, Arizona (USA) < fortean1 at mindspring.com >
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