Nuclear fusion at room temperature

New Delhi: It's the promise of a miniature sun on every table. But that is still some time in the future.

Nuclear fusion is what makes the sun the sun. Till recently, it was thought that, unlike fission, nuclear fusion required extremely high temperatures and pressure - quite like the insides of the sun.

Researchers at Rensselaer Polytechnic Institute have developed a tabletop accelerator that produces nuclear fusion at room temperature.

This provides confirmation of an earlier experiment conducted at the University of California, Los Angeles (UCLA), while offering substantial improvements over the original design.

While this doesn't immediately translate into a power generating sun in every home, scientists are suggesting that there are practical applications galore for this device almost immediately.

The device, which uses two opposing crystals to generate a powerful electric field, could potentially lead to a portable, battery-operated neutron generator for a variety of applications, from non-destructive testing to detecting explosives and scanning luggage at airports.

The new results are described in the February 10 issue of Physical Review Letters.

"Our study shows that 'crystal fusion' is a mature technology with considerable commercial potential," says Associate Professor of Mechanical, Aerospace and Nuclear Engineering at Rensselaer Yaron Danon.

"This new device is simpler and less expensive than the previous version, and it has the potential to produce even more neutrons," he adds.

The device is essentially a tabletop particle accelerator.

At its heart are two opposing "pyroelectric" crystals that create a strong electric field when heated or cooled.

It is filled with deuterium gas - a more massive cousin of hydrogen with an extra neutron in its nucleus.

The electric field rips electrons from the gas, creating deuterium ions and accelerating them into a deuterium target on one of the crystals.

According to Danon, when the particles smash into the target, neutrons are emitted, which is the telltale sign that nuclear fusion has occurred.

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A research team led by Professor of Physics at UCLA, Seth Putterman, reported on a similar apparatus in 2005, but two important features distinguish the new device.

"Our device uses two crystals instead of one, which doubles the acceleration potential," says a graduate student in nuclear engineering at Rensselaer Jeffrey Geuther and lead author of the paper.

"And our setup does not require cooling the crystals to cryogenic temperatures - an important step that reduces both the complexity and the cost of the equipment," he adds.

The new study also verified the fundamental physics behind the original experiment.

"This suggests that pyroelectric crystals are in fact a viable means of producing nuclear fusion and that commercial applications may be closer than originally thought," says Danon.

"Nuclear fusion has been explored as a potential source of power, but we are not looking at this as an energy source right now," he adds.

The most immediate application may come in the form of a battery-operated, portable neutron generator.

Such a device could be used to detect explosives or to scan luggage at airports, and it could also be an important tool for a wide range of laboratory experiments.

The concept could also lead to a portable x-ray generator, according to Danon.

"There is already a commercial portable pyroelectric x-ray product available, but it does not produce enough energy to provide the 50,000 electron volts needed for medical imaging," he says.

"Our device is capable of producing about 200,000 electron volts, which could meet these requirements and could also be enough to penetrate several millimeters of steel."

In the more distant future, Danon envisions a number of other medical applications of pyroelectric crystals, including a wearable device that could provide safe, continuous cancer treatment.

Frank Saglime, a graduate student in nuclear engineering at Rensselaer, also contributed to the research.

(Source: Rensselaer Polytechnic Institute)