Sandia Labs Takes First Steps Toward Fusion 371
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."
putting that subscription to good use (Score:5, Informative)
Perhaps somebody could explain to me why it seems as though the electricity is staying on a certain plane instead of moving on the y axis as well? My guesses: the room is filled with a non-conducting liquid and the elevctricity is scattering about on top of it, or there is an electromagnetic field that the electricity is sitting upon, but it's being pulled down hence why it's not moving up any more.
Note: as of the time of this posting, it's still uploading and dialup still sucks.
Woohoo! (Score:3, Informative)
article (Score:2, Informative)
Z produces fusion neutrons, Sandia scientists confirm
PHILADELPHIA, Pa. -- Throwing its hat into the ring of machines that offer the possibility of achieving controlled nuclear fusion, Sandia National Laboratories' Z machine has created a hot dense plasma that produces thermonuclear neutrons, Sandia researchers announced today at a news conference at the April meeting of the American Physical Society in Philadelphia.The neutrons emanate from fusion reactions within a BB-sized deuterium capsule placed within the target of the huge machine. Compressing hot dense plasmas that produce neutrons is an important step toward realizing ignition, the level at which the fusion reaction becomes self-sustaining.
The amount of energy a larger successor to Z could bring to bear offers the still-later possibility of high-yield fusion -- the state in which much more energy is released than is needed to provoke the reaction initially to occur. The excess energy could be used for applications such as the generation of electricity, said Tom Mehlhorn, a project leader on the machine.
Z causes reactions to occur neither by confining low density plasmas in dimensionally huge magnetic fields, as do tokomaks, nor by focusing intense laser beams on or around a target, as in laser fusion, but simply through the application of huge pulses of electricity applied with very sophisticated timing. The pulse creates an intense magnetic field that crushes tungsten wires into a foam cylinder to produce X-rays. The X-ray energy, striking the surface of the target capsule embedded in the cylinder, produces a shock wave that compresses the deuterium within the capsule, fusing enough deuterium to produce neutrons."Pulsed power electrical systems have always been energy-rich but power-poor," said Ray Leeper, a Sandia manager. "That is, we can deliver a lot of energy, but it wasn't clear we could concentrate it on a small enough area to create fusion. Now it seems clear we can do that."
A partial confirmation of the result came about when theoretical predictions and lab outcomes were determined to be of the same order of magnitude. Predictions and measurements of the neutron yield were both of the order of 10 billion neutrons. The predicted neutron yield depends on the ion density temperature and volume. Those quantities were independently confirmed by X-ray spectroscopy measurements.Neutron pulses were observed as early as last summer but researchers were wary that the output was produced by interactions between the target and ions generated by Z's processes, rather than within the capsule itself. Ion-generated neutrons were not the point of the experiment, since they would not scale up into a high-yield event in any later, more powerful version of Z.
But a series of experiments completed in late March demonstrated that the production was within the capsule itself. To show this, researchers inserted xenon gas within the capsule. The gas prevented the capsule from getting hot during compression. Thus, the neutron yield dropped dramatically, as predicted.The action takes place within a container the size of a pencil eraser, called a hohlraum, at the center of the Z machine, itself a circular device about 120 feet in diameter.
Sandia researchers Jim Bailey and Gordon Chandler led the experimental team and Steve Slutz performed theortical calculations. Sandian Carlos Ruiz and Gary Cooper of the University of New Mexico performed the neutron measurements.Re:the lower the density the easier you float. (Score:2, Informative)
Higher density = heavier = you are relatively lighter = float
Lower density = lighter = you are relatively heavier = sink
I Mirrored This Article (Score:3, Informative)
Re:Fusion isn't clean (Score:4, Informative)
I'm not sure if I've got all of that right, but I think it's more or less accurate.
Re:Z-what? (Score:2, Informative)
The photo of a firing of Sandia's Z accelerator shows, in the brilliant arcing of electricity, only the trace amounts of energy that escape. The reaction actually releases, in X-rays, roughly 80 times the entire world's output of electricity for a few trillionths of a second.
It is within this plasma that the reactions take place. The electrical discharge on top is not where the real action takes place.
Re:Fusion isn't clean (Score:3, Informative)
Huh? Most of the waste from conventional fission plants is spent fuel and its byproducts, like Cesium-137 (one of the worst pollutants from Chernobyl). Protection against neutron radiation has always been through very thick concrete walls, and obviously those don't get thrown away. I don't know anything about the neutron output of fusion, but the principal "byproduct" is helium rather than various nasty heavy isotopes.
Re:Z-what? (Score:3, Informative)
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.
Hybrid Quesion (Score:5, Informative)
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 :-)
That Liquid == Non conducting oil (Score:4, Informative)
The liquid in the tank is a non-conducting oil, used to insulate the various components submerged within this oil. I would assume that this oil is similar to what you would find in commercial and industrial grade transformers. The oil in transformers prevent arcs from crossing one coil of particular voltage/current to the other one. But, this oil still allows the magnetic fields of one of the coils to influence the electrons in the other, thus allowing the transformers to do what they are ment to do.
And if you didn't know how transformers work, they operate by on one side, you have a coiled up wire (specific number of coils) with specific voltage and current running through those wires. When you make a coil of wire and pass a current through it, you create a magnetic field. Well, the transformers are designed so that the first coil of wire is sitting next to another coil of wire (with different # of coils or wraps) and the first coil with electricity running through it induces a magnetic field in the second coil. And because of the different # of wraps in the second coil of wire, you get a current running through that second coil of different amperage (current) and voltage. Effectively, this transforms the electricity from one voltage/current to another! EUREKA!
So the oil in these transformers are good insulators to prevent the two coils of wires from arcing, and thus maintaining the functionality of the transformer. If you allowed the coils to arc, there is really no point in having a transformer.
You see those little barrels on the power/telephone poles right? Those are transfering high voltage, low current, to 110V and high current for your house!
Due to thermal energy loss in wires with high current over long distances, the power companies in the USA transform the power in to high voltage/low current for the journey to your house, and then back to low voltage/high current electricty for use in your home.
Hope that helps!
Re:Fusion isn't clean (Score:5, Informative)
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.
More accurate energy numbers. (Score:5, Informative)
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.
Re:Can't Stress This Enough... (Score:2, Informative)
I spend between 2-8% of my monthy income (net) on my power bill, Probably 2% in the winter, closer to 8% in the summer. Say the end result of the Fusion was that my electic bill ended up being cut in half - that in it self would make up for the COLA "raise" I got this year.
Either you make a LOT more than I do, electric is cheaper where you live, or you use a LOT less electric than I do.
Re:Fusion isn't clean (Score:2, Informative)
Tritium isn't but it is a low energy beta emitter which can't penetrate human skin.
Fusion does produce neutrons, so you deal with it through a neutron absorber like boron carbide.
Fusion is much cleaner than fission.
Re:Practical fusion at home! (Score:5, Informative)
Evidently the problem with the better design is that once the fusion threshold was reached the temperature of the fusion plasma rose high enough to keep the ion injectors from being able to add new fuel to the plasma.
Farnsworth's better tube creates an almost ideal plasma:
As far as I know nobody has rebuilt the more complex fusor tube to try improving on the Farnsworth design. That design was brilliant. It is not obvious how the tube works until you realize that the virtual electrode produced by the electron cloud at the center of the tube is partially canceled by the ions injected into the center - which allows more electrons to concentrate in the virtual electrode - which allows more ions - etc. This allows a very dense plasma to be generated.
The truth is Farnsworth created more fusion in his desktop experiments than any of the giant, big money, fusion experiments since.
Re:Fusion isn't clean (Score:4, Informative)
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.
It's not that simple ... (Score:5, Informative)
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.
The impact will be zilch. (Score:5, Informative)
We've already got one (Score:2, Informative)
Once again, the boondoggle continues to roll on, sucking up billions of dollars of U.S. tax dollars chasing the promised "clean" fusion energy that would make everything cheap and simple. Let me point some things out to you guys:
And why are we persuing this hopeless mirage like Ponce de Leon, starving in a land of plenty? I, personally, have no idea. Hey, dipshits. Look up. You see that big bright ball of light? It's called the Sun and it's a functioning, efficient fusion generator just pouring it's useful energy (in the form of visible and near visible light) out at us. And why is the energy so useful? Because the dirty fusion by-products have been filtered into heat and light by ~500k km of Sun stuff situated between us and the fusion. (And don't give me that shit about solar panels costing more energy to make than they produce. You don't need to convert it directly into electricty, do you?). If solar energy is so damn inefficient, how do you think our entire planet got along until now? Even oil is solar energy filtered through a couple generations of conversion.
It seems to me that the main problem holding solar energy back is the lack of efficient, large scale, energy storage facilities. Hey, give me a billion and I'll make a couple for you and we can get off of this fusion chase, and start generating useful energy. From the sun. Like the rest of the Earth.
Re:Holy grail of energy? (Score:3, Informative)
This is most likely what will fuel starships, when intelligent life here has the resources to build them. (note I said intelligent life : human beings would (probably) never be able to ride these starships, nor would be the builders of them)
Due to the danger posed by the tiniest particle at 80-90% of c, I think these starships would be very very very narrow while crossing the gulf. Only when changing velocity (near the beginning and end of the trip) would they self assemble into a large structure with enough mass to stop the particles produced by the anti/matter annhilation.
I think the actual "payload" would be extremely small : a few hundreds kilograms or less. These would be micromachines capable of exploiting the resources found at the destination. The actual passengers would be sent by quantum teleportation (basically a steam of particles and entangled pairs that would be receieved by the vessel once it has had time to construct a receiver upon arrival. As the ship travels, the micromachines would constantly have to repair damage to it, and would have their programming continuously updated by the beam of information sent from their starting point.). The "passengers" would be information embodying whatever lifeforms wish to explore/exploit the target system. In theory these particles could be pieces from a human mind, but I think this unlikely as meatware isn't very fast or efficient. Basically, most of the ship would be the information sent after it leaves, with only a relatively small mass actually experiencing the speeding up and slowing down.
Comment removed (Score:3, Informative)