Slashdot Mirror
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 seems to be the ultimate goal for energy. Offering a
clean and abundant power supply that could potentially alter our
entire power production system. One of the problems with the
transition to a hydrogen based economy has been that energy is
required to extract the hydrogen from known reserves (petroleum,
water, etc). The most common solution offered seems to be solar
powered systems, however fusion could offer a great alternative
which in the long run may prove more viable and more extensively
useable than solar, hydro-electric, or wind power individually,
maybe even collectively.
It's particularly encouraging to see the scientists questioned
their results and tested for extraneous sources before
publishing preliminary findings.
Doug Tolton
"The destruction of a value which is, will not bring value to that which isn't." -John Galt
...however fusion could offer a great alternative which in the long run may prove more viable and more extensively useable than solar, hydro-electric, or wind power individually, maybe even collectively.
Yeah, but can I hook one up to a DeLorean and do time travel?
The opposite of progress is congress
So can I play Zork on this thing or what?
-_-_-
There are 0x40000000 types of people: those who understand 32-bit IEEE 754 floating point, and those who don't.
Talk about a wild desktop background!!!
How long until the lights go out and demons from another dimension are sucked into the building?
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.
I mirrored this article, including the images, on my website (a quick one hosted with Yale.edu bandwidth) in case the main link goes down: Here is the Mirror
I'm not sure if I've got all of that right, but I think it's more or less accurate.
My only political goal is to see to it that no political party achieves its goals.
http://www.sandia.gov/pulspowr/facilities/zacceler ator.html
Basically, these guys store a whole lot of electricity in monstrous capacitors, and then shove all of it through a contraption of parallel wires (imagine about a hundred wires lining the inside of a Pringles can -- parallel to the can's long axis -- the "z" axis in cylindrical coordinates, and then take away the can).
From the Lorentz force law (easiest way to see this; alternate explanations work, too, but everything boils down to the same thing), one can see that parallel wires, when they have current going through them in the same direction, attract each other. So these wires, each of which has gazillions (technical term) of Coulombs per second coursing through them -- Amperes), get attracted to eachother VERY much. These attracting wires basically "pinch" whatever is put between them, possibly leading to fusion (in deuterium, the article states).
Now, to add to the complexity, take away the wires. They get vaporized by the huge currents going through them, and basically you've got lines of plasma (positive and negative ions -- which allow current flow) which accelerate together, making for the pinch effect.
This all happens very, very quickly, and at nice high temperatures (thus thermal energy also helps contribute to fusion effects), so that fusion is kept on the edge of possibility.
The pretty sparks in the pictures are produced when those capacitors discharge -- there's a "skin" effect on the oil, where its surface is next to the air. Those big sparkies, are, in effect, just the spark from a very large, very expensive finger approaching a very large, very expensive doorknob on a nice dry day, after the very large, very expensive feet have been scuffed over a shag carpet.
From the outside it looks to be a competition, and mutually exclusive at that. What are the possibilities of hybridizing these methods? Could all 5 approaches come together and cooperate towards solving this puzzle? I can even suggest a few new Fusion approaches of my own.
Fusion is generally considered clean compared to Fission, at least in direct by-products (your containment vessel is another matter due to high-energy neutron bombardment). Could we abandon the completely clean approach to get across the finish line, and then improve towards pure forms of Fusion? By this I mean Fusion-Fission hybrids similar to an H-Bomb, which uses the neutron burst (and heat and compression) from a fission reaction to trigger a fusion reaction. Would seeding our deuterium-tritium pellets with cores of plutonium, or other more unstable isotopes, yield better conversion ratios? Can micro critical masses be achieved by compression with fissionable products? How about micro fission generators, that rely on micro fission explosions. Then like our theoretically perfect fusion reactors, it would be impossible to go critical, because you would never have the fuel density to achieve run away fission (take away the compressive mechanism, no fission).
Anyway I'm just a lay person, but I figure there should be a few good Physicists in the forum, that could answer my core question about whether there a hybrid approaches being tired. I would be especially intrigued to learn if muon catalyzation has been tried with any of the other 4 approaches. For those unfamiliar with muon catalyzation, the essential idea is that an electron can be displaced by a muon for short periods of time, with a subsequent huge reduction in the size of the electron/muon orbital cloud, allowing atoms to come much closer together before mutual repulsion forces them apart. Thus a much lower thermal energy is needed for fusion -- hope I got that right :-)
Letter To Iran
IIRC, President Bush mentioned in his recent State of the Union address funding research into alternative energy sources in general and fusion in particular. Now that Sandia has made some new headway, will we start seeing more money flowing into the DoE and Sandia?
I personally can't wait until the Middle East once again becomes a red herring...
Even if we leave aside the radioactivity of deuterium and tritium
Deuterium is stable. Tritium decays by emitting a low energy electron so if you're carrying a big chunk in your pocket it might sterlize you at worst. Rain water contains tritium so it's not like the world can't cope with it.
The main byproduct of nuclear fusion is helium-4 which hardly qualifies as radioactive waste.
:wq
Harnessing energy release is what all generators are about. It's not the release of energy that is difficult, but the efficient release and harness. :)
Coal/oil/gas generators all generally heat water, turning it into steam, spinning a turbine to produce mechanical energy which is converted to electricity through induction.
Fission also releases massive amounts of heat energy which is absorbed by water and turns a turbine.
The majority of energy in these fusion reactions (Inertial confinement fusion (laser driven), magnetic confinement fusion (in a tokamak), electrically pulsed like in this article) leaves the system in the kinetic energy of the resulting particles. For example, Deuterium and Tritium are often fused yielding normal Helium and a neutron. Both are moving very fast after the fusion. This velocity is where most of the energy of fusion is. You can capture this again by letting the fast particles transfer their energy to a big resorvoir which would heat up from this energy transfer and again heat water to steam to turn a turbine.
With matter-antimatter collisions, the gamma rays would have to be absorbed by some matter, which energizes the matter, either thermally or electrically (that's how solar cells work - by liberating electrons by light interaction) or some other means I can't think of.
But you have to find the antimatter first
-Leo
BEGIN RANT
You just made my foes list due to your extreme lack of understanding. I don't know who your friends are, but they have been feeding you FUD!
This sounds just like the same sort of drivel that comes from the eco-morons when they start talking about how microwave ovens are bad for you because of the *nuculer* rays they emit, and go on about how irradiated food is radioactive. BLAH BLAH BLAH
Just FYI. I was raised in a volkswagon microbus and still have hair down to my butt, however I am also graduate student in physics. Please get a real education before spouting off with inane drivel!
END RANT
There are certain fusion reactions that can take place with *no* hard radiation. So you cannot just toss all fusion reactions into the same generalization. Further, as someone pointed out below the half life of irradiated neutron shielding can be very low, on the order of years rather than tens of thousands of years. As such it does not pose the same environmental hazard as spent fission fuel.
-- The morphemes of your disquisition are ascertainable, but they have eschewed an ambit of transpicuous exposition.
Oooooooooo.....
SB
It's old. The more humans I meet, the more I like my cats. At least they are honest.
From http://home.earthlink.net/~jimlux/nuc/reactions.h
Good luck getting your hands on tritium. Deuterium can be bought, or produced yourself with patience. Other reactions have very high threshold energies.
Note that this energy still isn't enough to penetrate the Coulomb barrier - it's the best tradeoff point between getting the particles close together and keeping them nearby long enough for there to be a reasonable chance of quantum tunnelling taking you through the barrier. So, most collisions will still just cause scattering.
Also note that any system involving a lot of scattering becomes Maxwellian (has a Maxwell-style temperature distribution). The fusor functions best in non-Maxwellian regimes. When the plasma thermalizes, it gets much colder due to the presence of cold ions (or cold, neutral molecules) from the source gas.
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...
That was what surrounded the linear accelerator at my university. Parafin and other hydrocarbons also work. Basically, anything with lots of hydrogen atoms. Since a neutron is very close in mass to a proton, when a neutron hits a hydrogen atom you get a good chance of
H + n -> D
and deuterium is good and stable. Of course the D + n -> Tritium, which is radioactive, but can be dealt with reasonably easily.
Beta radiation, being charged, just needs some tinfoil. Gamma though needs lots and lots of concrete, or lead.
No, neutrons are easy to deal with, and anyway, my children find their extra limbs surprisingly useful.
Protoplasm. Quiet Protoplasm. I like quiet protoplasm.
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.
I wouldn't consider 100 year helf lifes to be "long". I would term that intermediate at worst. Long is 240,000 year half lifes. We can actually contain stuff for a few hundred years until it decays.
just my $.02
It's not as simple as that. The temperatures and pressures needed to fuse helium into heavier elements is several magnitudes above what is needed to fuse hydrogen into helium. The energy expenditures needed would far outweigh the current cost of obtaining these elements.
A good way to research the topic of fusion is to look up information on the formation and life cycle of stars, nature's fusion reactors. You'll find that as very massive stars age, they burn through their hydrogen fuel quickly. Once that's all used up, gravity threatens to collapse them, until temperature and pressure in the core raises to the point that fusion into heavier elements can happen.
But then you'll see that the first steps of the heavier fusion processes create very common elements: carbon, oxygen, nitrogen. That's precisely why these elements are so abundant. By the time you get to elements even remotely rare, you're talking pressure and temps on astronomical scales. Finally, in the very massive stars, fusion can't go any further than iron, because after iron, fusion reactions no longer yield energy, but absorb energy. So after iron, it becomes an even more uphill battle.
Most likely if we do ever manage to harness fusion, it will stop at helium, as that will serve our needs well.
Karma: Frotzed (mostly due to the Frobozz Magic Karma Company)
As long as the helium released is made of stable isotopes, it will have little to no effect. The Earth has insufficient gravity to retain either hydrogen or helium in significant quantities. The helium will basically waft away into space. If helium could be retained in the atmosphere Earth would be a gas giant.
will explain a bit more slowly: it doesn't matter all that much if we do develop fusion power b/c it will be completely under the control of CorpGovMedia. Why should they offer fusion power cheaper than its primary competitor, oil?
Can you name me any technology that hasn't gotten cheaper over time? CD players? Microwave ovens? Cars? Cell phones? Wristwatches? Calculators? Even electricity itself is getting cheaper and cheaper every year, allowing for inflation.
I'm afraid it is you who needs the slow explanation. New technologies always supplant old, and there's nothing that anyone can do about it. I can imagine people like you trying to explain that the car would never replace the horse, or that airliners would never replace steam trains.
THis is because we have no control over CorpGovMedia....
You are correct, people like you with no understanding of technology or economics have no control over anything. Fortunately for the rest of us, you don't matter.
Not exactly the reason they use hydrogen. It is close in mass to the neutron so there is efficient transfer of energy to the hydrogen, which means the neutron slows down fastest in hydrogenated materials. So, the neutron "thermalizes" quickly in water, and it can be more readily absorbed by other things that have a higher reaction rate...like boron. And let me tell you, the neutrons coming from a fusion reaction aren't "easy" to deal with. They take a lot of slowing down before they get into an energy regime where they are easily absorbed. But, it can be done. Take it from me...I'm a nuclear physicist.