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Sandia Labs Takes First Steps Toward Fusion
robosmall writes "Sandia Labs has successfully demostrated the emission of neutrons (a side effect of thermonuclear fusion) from a BB-sized capsule of deuterium using using their venerable Z-Machine (eye-candy!). With this achievement they enter the race to create sustained fusion reactions."
Fusion research isn't just for the big guys - you can build a Farnsworth-Hirsch fusor at home! Seriously, these things are capable of fusing hydrogen when built properly. I think they're only like 1% efficient at generating power, but it looks like there's still some room for experimentation. You could probably put one together for a few hundred bucks if you're good at scavenging. The biggest danger really isn't from neutron emission, it's from working with vacuum equipment. I wouldn't want to be near a glass bell jar when it implodes. Still, it'd be worth it just to have a cool, glowing fusion reactor in the garage.
Not even close. Matter / anti-matter based reactors would be orders of magnitude more efficient.
"Clean fusion" is a myth. Even if we leave aside the radioactivity of deuterium and tritium, fusion produces neutrons. These neutrons bombard everything in the vicinity. If fusion goes big-time, that means that just as with fission reactors, very large quatitites of radioactive waste will be generated. Remember, most fission-plant waste is not fuel, but other substances that are exposed to the neutrons. Of course, fusion is better on other fronts, but not all that much cleaner.
Make cheese not war 8:)
Why would we content with helium as output? Ok, as a first step, lets get there first, but would it be relatively easy to produce heavier elements than helium? Elements which are rare and expensive to mine?
Remember the year 2000? They promised us flying cars. They delivered the PT Cruiser...
Ok, what would the impact of releasing helium into the atmosphere be? Yes, helium is an inert gas, but over a millinium, could helium account for say, 5% of the atmosphere? Could oxygen levels, as a percentage of air, fall? Can helium contribute to the green house effect, or counter it? What color will the sky become? Are tenors an endangered species? :)
Anybody has calculations on how much helium is expected to be produced worldwide when fusion becomes commercial?
Remember the year 2000? They promised us flying cars. They delivered the PT Cruiser...
They got the H-bomb to work using a staged approach. Stanislaw Ulam had the original idea for a staged advice, but the final Ulam-Teller device used x-rays rather than the shock blast from the A-bomb, reflected or reemitted from a U-238 jacket, to energize, of all things, Styrofoam as an imploder. That didn't set off the fusion reaction either, but it imploded a plutonium "spark plug" that gave off enough neutrons to set off the deuterium, which in turn produced most of its energy in neutrons that acted on the U-238 jacket that gave most of the yield of the device.
I have now idea (or care to have) whether modern, compact warheads use the same principle as Ivy Mike. But I bet that the National Labs have tons of experience with variants of these Rube Goldbergesque "staged" devices. Now the Z-machine is a staged device -- instead of using x-rays, it uses buckets of electric current to implode this little wire cage surrounding a pellet. You don't apply energy directly to the deuterium but to something else which in turn implodes the deuterium.
Besides its Bomb heritage, the method has more ominuous applications. Long before this device is useful as an electric power generator, it will be useful for generating bursts of neutrons. To do what? To simulate mini H-bomb blasts of course. I believe the U.S. has signed or pledged or whatever to suspend all nuclear tests. While some believe that the people in the Bomb business are atomic-pyros who can't get enough of testing, suspending nuclear tests means that over time we are giving up are nuclear military arsenal because bombs get old and without testing you can't be sure if they are going to work as promised. There are two answers to that. One is computer simulation with clustered computers and all the Beowolf-cluster jokes on Slashdot. The other is to use the Z-machine to make little bursts of neutrons to do sub-scale H-bomb tests.
The article says the reaction yielded 10 billion neutrons; for simplicity's sake I'll assume that's one neutron produced per fusion reaction and 15MeV released per reaction (I think the 15MeV is from deuterium-tritium reactions, and the article just mentions deuterium as a fuel, but oh well). So that gives:
I don't mean to cast aspersions on the experiments or experimenters; it's just that we're still a long way (I suppose) from making a breakeven fusion reactor.
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