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 is Good but Buoyancy is Better

[Michael.Forman]

I've worked at Sandia for two years (this week) and cannot overstate how sci-fi it is to work there.

During a tour given to new hires, I was able to walk on top of the Z-Machine [sandia.gov] and peer into the tank. Seeing my curiosity, the leader of the tour took the opportunity to tell us that the system is completely submerged in a tank of oil to prevent electrical breakdown during tests. He followed with a warning, that not even an Olympic swimmer would be able to remain afloat in the oil, due to its low density. In the event of an accident, he instructed us to walk along the bottom of the tank to a ladder and climb out.

Michael. [michael-forman.com]

Practical fusion at home!

[Rorschach1]

Fusion research isn't just for the big guys - you can build a Farnsworth-Hirsch fusor [wikipedia.org] 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.

Holy grail of energy?

[Anonymous Coward]

Not even close. Matter / anti-matter based reactors would be orders of magnitude more efficient.

Fusion isn't clean

[abbamouse]

"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.

Re:Holy grail of energy?

[NoMoreNicksLeft]

For antimatter to be practical, you'd have to find some exotic reaction that creates more anti-matter than it consumes (in fission this would be a breeder reactor). Short of some undiscovered flaw in M/AM symetry, I don't think this is even possible. (Then again, there must be some mechanism that cause matter to be predominant during the big bang... maybe we could reverse it?)

At most, antimatter would be like hydrogen, but for ultra-dense storage.

Re:Fusion isn't clean

[NoMoreNicksLeft]

Beta radiation can be shielded against with tinfoil, iirc? True?

Only tokamaks stand any chance of being radioactive in a pollution sense. The CRT I'm sitting in front of is likely more dangerous than Zpinch...

No chance of a meltdown, spent fuel is helium, hospital radiology labs produce more waste... what's the parent poster's problem?

Why stop with helium?

[deragon]

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?

Impact of releasing helium into the atmosphere.

[deragon]

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?

Mini H-bomb

[Latent Heat]

The Z-experiment or whatever they call it is the closest to the actual H-bomb of all the fusion approaches. The actual H-bomb doesn't work by simply sticking an A-bomb at the end of a tube of deuterium. Teller thought such a "classic Super" would work but computer simulations proved him wrong. Its probably a Good Thing the Classic Super doesn't work because A-bombs or H-bombs could ignite their surroundings and set off the whole Earth in a nuclear conflagration.

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.

Re:Potential amount of energy involved?

[NewbieProgrammerMan]

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:

(10^10 fusions) * (15*10^6 eV/fusion) * (1.6*10^-19 J/eV) = a whopping 0.024J.

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.

Long-term solution

[Jeppe Salvesen]

Sure, fusion offers a long-term solution. However, the emissions of carbon dioxide occur right now.

Wind power, nuclear power, solar power, hydro power and wave power all provide electricity without releasing CO2.

Interestingly, burning organic material (like wood) is also OK on a global scale. Not only is the Carbon already part of the circulation, but the aerosols have a cooling effect.