Two UK organisations have formally joined forces with a US laser lab in an attempt to create a working version of laser fusion. The National Ignition Facility (Nif) in the USA is drawing closer to producing a surplus of energy from the idea, and UK company AWE together with the Rutherford Appleton Laboratory have now joined with Nif to help make laser fusion a viable commercial energy source.
At a meeting earlier this month sponsored by the Institute of Physics and held at London's Royal Society, a memorandum of understanding was announced by the three facilities.
"This is an absolutely classic example of the connections between really high-grade theoretical scientific research, business and commercial opportunities, and of course a fundamental human need: tackling pressures that we're all familiar with on our energy supply," said David Willetts, the UK's science minister.
The UK has a long heritage in a different approach to accomplishing fusion, one which uses magnetic fields for containment; it is home to the Joint European Torus (Jet), the largest such magnetic facility in the world and a testing ground and forerunner for Iter, the International Thermonuclear Experimental Reactor.
But magnetic fusion attempts have in recent years met more and more constricting budget concerns, at the same time that Nif was nearing completion.
Part of the problem has been that the technical ability to reach "breakeven" - the point at which more energy is produced than is consumed - has always seemed distant. Detractors of the idea have asserted that "fusion energy is always 50 years away, no matter when you ask the question".
But Mr Willetts told the meeting that was changing. "I think that what's going on both in the UK and in the US shows that we are now making significant progress on this technology," he said. "It can't any longer be dismissed as something on the far distant horizon."
The Rutherford Appleton Lab is where the idea of fusion energy was first proved, and both that laboratory and the AWE have high-intensity lasers that can act as proving grounds for future technology.
Laser fusion uses pellets of fuel made of deuterium and tritium. A number of lasers are fired at the pellets to compress the fuel to fractional pecentage of its size. In the process, the hydrogen nuclei fuse to create helium and high energy neutrons. In the NiF version 192 laser beams are focused through holes in a target container called a hohlraum. Inside the hohlraum is a 2mm pellet containing an extremely cold mixture of hydrogen isotopes. Lasers strike the hohlraum's walls, which in turn radiate X-rays. The X-rays strip material from the outer shell of the fuel pellet, heating it up to millions of degrees and compressing the fuel. If the compression great enough and uniform enough, the deuterium and tritium can fuse, creating helium and releasing "hot" neutrons. The aim is to achieve "ignition" of the fuel, the point at which the reaction becomes self sustaining and would create an enormous heat surplus. Nif's director Ed Moses told the meeting that point, ignition, was drawing ever nearer."Our goal is to have ignition within the next couple of years," he said.
•The UK also leads the High-Power Laser Energy Research (Hiper), a pan-European project begun in 2005 to move laser fusion technology toward a commercial plant.
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