UK Joins Laser Nuclear Fusion Project

arisvega writes with this quote from the BBC: "The UK company AWE and the Rutherford Appleton Laboratory have now joined with [the National Ignition Facility in the U.S.] to help make laser fusion a viable commercial energy source. ... 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 50 years away, no matter what year you ask,' said David Willetts, the UK's science minister. '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.'"

Re:FTA: what they're actually doing

[Anonymous Coward]

"Dr Moses said that a single shot from the Nif's laser - the largest in the world - released a million billion neutrons and produced for a tiny fraction of a second more power than the world was consuming."

The power is completely irrelevant. What matters is the time integral of the power, that is, the energy. Also, a million billion neutrons is only 10^15, at most a kilojoule of total energy (probably a lot less than that). To put that in perspective, the energy that a 1 kilogram hammer releases (at high power) if you drop it 100 meters to inelastically collide with a bucket of sand. The important questions are: a) Did it cost more energy to produce that shot than was released? If so, we still haven't reached break even, and without break even no, it isn't a viable energy source. b) Did it produce at least four or five times (ideally ten or more times) as much energy as was required to make the shot? If not, we haven't reached break even on conversion efficiency and transmission efficiency from those neutrons to the factory or household. c) Does it take one whole second of e.g. charging up capacitor banks and so on to create the nanosecond or ten flash of energy at such high power, so that one can never achieve an integrated power release higher than a few tens or hundreds of watts (per enormous laser)? If we assume a whole kilojoule per event, one has to be able to fuse 1000 events per second to make a humble megawatt, one million events per second to make a gigawatt (the size of a respectable power plant) and one really needs to make at least 5 gigawatts of sustained power to be sure of delivering 1-2 GW to the consumer. Popping 5 million little fuel capsules per second, even with a bank of lasers and delivery systems, presents some truly awesome engineering challenges, especially if all of those fuel capsules require careful engineering in and of themselves.

I've never been terribly optimistic about laser driven fusion. Well, since I was around 10 years old (back in the 60's). I was all over it then, and designed endless fusion driven engines using lasers to achieve ignition. But then I studied actual physics...

rgb