[ RadSafe ] FW: Crystal fusion!

[A Karam]

A science writer colleague sent this to me.  It sounds legitimate - not
at all like the "cold fusion" fiasco in the late 1980s.  Interestingly,
this story also notes the possibility of using this device in place of
radioactive sources for some applications.  Wouldn't it be nice to have
a pocket-sized device to generate radiation as, say, a gauge or well
logging source, instead of having to use radioactive materials?

Andy

-----Original Message-----

Crystal creates table-top fusion
Mark Peplow
It won't solve our energy crisis, but could help treat cancer.


A piece of plastic (2.5cm across) loaded with deuterium atoms glows blue
where an incoming beam of deuterium triggers fusion.
(c) Seth Putterman, UCLA
At first, it sounds like the biggest science story of the century:
scientists have invented a desktop fusion machine.

If nuclear fusion can be made to happen at room temperatures and
pressures in an average lab, then one might think the world's energy
crisis is over. But the inventors of the device stress that their gadget
cannot generate power at all, because it does not support a
self-sustaining thermonuclear reaction. Instead, they say, it has a
whole host of other applications, from treating cancer to powering
spacecraft.

The inventors are led by Seth Putterman, a physicist from the University
of California, Los Angeles. Putterman is known for debunking claims of
'bubble fusion' and 'cold fusion' that promised revolutionary advances
in energy production.

His toaster-sized device, detailed in this week's Nature1, relies on a
pyroelectric crystal of lithium tantalate, which produces a strong
electric field when heated to room temperature from freezing. This field
is focused until it is powerful enough to accelerate a beam of deuterium
ions (proton-neutron pairs) to about 1% of the speed of light.

When these ions hit a target containing deuterium nuclei, they fuse to
form helium-3, a combination of two protons and a neutron. The process
emits about 1,000 neutrons a second, and by allowing the crystal to heat
up slowly, fusion can be sustained for as long as eight hours.

Low-power wonder

This type of fusion is already used in commercially available
instruments that determine the chemical composition of materials at a
distance. Such devices blast neutrons down to the bottom of oil wells,
for example, to determine the quality of oil. They are also used at
airports to study in detail the contents of suspicious luggage.

However, such applications currently require bulky, expensive particle
accelerators with large electricity supplies. Replacing those with a
small crystal is a big step. "The amazing thing is that the energy
fields of a crystal can be used without plugging it in to a power
station," says Putterman.

"They've built a really neat little accelerator," agrees Mike Saltmarsh,
a nuclear physicist formerly at Oak Ridge National Laboratory,
Tennessee.

It will probably make its first big splash in labs looking for an easy
neutron source. But, predicts Putterman, "there will be a lot of
spin-offs from this technology".

Radiation on tap

"Everyone will be talking about the fusion, but this crystal can also
give off X-rays as it accelerates electrons," says Putterman. This
effectively creates a tiny radioactive source that can be turned on and
off at will. Such a device could one day be used to target radiation at
cancerous cells: a smaller version could be injected into the body and
directed towards a tumour before being switched on. In contrast, today's
radiation therapies tend to blast healthy cells along with cancerous
ones.

Putterman also thinks that rocket propulsion could benefit. Space probes
such as the European Space Agency's SMART-1, which recently arrived at
the Moon, already use ion engines that eject a stream of charged xenon
gas to produce a gentle forward thrust. The pyroelectric accelerator
could produce a similar beam of ions moving at much greater speed, which
would increase the thrust considerably, says Putterman.

The team is now trying to boost the number of neutrons generated by the
machine, as well as miniaturizing the device even further.