First step toward making “little sun” as limitless energy source reported

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First step toward making “little sun” as limitless energy source reported

Nov. 25, 2005
Special to World Science

Scientists say they have taken a first step towards making a sort of miniature sun that could serve as a virtually limitless energy source.

The project, at Lawrence Livermore National Laboratory in California, would involve squeezing atoms until they merge, releasing energy in the process. This process, called nuclear fusion, is what makes the Sun shine.

In nuclear fusion as it occurs on the Sun, an atom of deuterium and an atom of hydrogen are forced together by high pressure into one atom, which then quickly releases a neutron. During the process, a small part of the mass of the original particles is converted into energy. (Image courtesy U.S. Heavy-Ion Fusion program)

Scientists have been working for decades to harness nuclear fusion because it’s thought that this would provide a clean, safe alternative to existing nuclear power plants. But technical hurdles and at least one widely publicized false claim of success have beset the research.

The Livermore project would use the world’s most powerful laser, called the National Ignition Facility and which is currently under construction, to heat a small, enclosed space.

In that space, scientists would place a container holding a frozen sample of a type of hydrogen. The heat would expand the container, forcing its contents into a smaller and smaller space until the atoms merge.

Livermore scientists reported in a new paper that in a test run without the container of hydrogen, the enclosed space generated enough energy in the form of X-rays to produce the necessary heating to make the project work.

The heat wasn’t sufficient for fusion, as only four laser beams were used of the 192 that would eventually come into play, researchers said. But the amount of energy generated matched computer simulations developed for the project, showing the work was on track, they added.

The findings were published in the Nov. 18 issue of the research journal Physical Review Letters.

It could take decades of additional work to convert this promising start into working power plants, said the laboratory’s Eduard Dewald. Fusion will be achieved “hopefully in 2010,” he said; further research will involve making the process efficient and quickly repeatable enough to generate power on a mass scale.

Existing nuclear power plants extract energy from atoms by splitting them up, a process called fission. The new research, by contrast, does it by forcing them together, a process known as fusion.

The reason these opposite processes can achieve the same result is that the types of atoms are different. Some types release energy when they’re forced together, others do so when they’re split up. Fusion energy research employs variants of hydrogen atoms called deuterium and tritium.

Another line of research toward harnessing fusion energy involves using magnetic fields rather than laser heating to confine the atoms. Last summer, an international group of scientists and politicians agreed to build an experimental fusion reactor in Cadarache, France, using that strategy.

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