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Team Confirms UCLA Tabletop Fusion
An anonymous reader writes "A team of New York physicists has confirmed that a tabletop contraption made at UCLA does in fact generate nuclear fusion at room temperatures, using pairs of crystals and a small tank of deuterium. But unlike less reliable reports back in the 1980s, there's no talk this time of producing endless supplies of power. Rather, the technology could lead to ultra-portable x-ray machines and even a wearable device that could provide safe, continuous cancer treatment."
From TFA: I'm surprised that the article didn't go into more depth on the explosives detection angle, as a neutron generator is an excellent method for detecting fissionable material, and I'm sure the folks over at Homeland Security would like a better way to guard against nuclear devices being smuggled into our country.
For more info on neutron generators and their possible application in fissionable materials detection, please look here (PDF warning).
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~ |rip/\/\aster /\/\onkey
It's quite an accomplishment. However, as the article noted, they don't mention even the remote future possibility of creating a self-sustaining reaction. So I'm assuming that there is no way even in principle this technology could be scaled to yield more power than it uses.
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I hope this works out as a decent power source
Sorry to disappoint, but it's just not going to happen. These types of methods of fusion are always going to require more energy input than output. Efficient artificial reactors may be possible in the future, but for now they remain a pipe dream--especially 'cold fusion' ones.
Take off every sig. For great justice.
No, we do not have cold fusion. This isn't a power source at all (i.e. over all the process is endothermic), we just have a small "neutron-making-machine".
The paper.
IANAP (I am not a physicist), but I do know that nuclear fusion doesn't create fallout like nuclear fission does.
Fallout is caused by one of two events:
1. Excess nuclear materials not consumed in the reaction are left behind.
2. The neutron radiation from the event interacted with nearby materials (such as the dirt on the ground) to create new radioactive materials.
Nuclear fusion is "clean" in that there are no radioactive materials left over from the reaction. However, it does produce an incredibly strong neutron flux which can easily create radioactive fallout in nearby materials.
http://en.wikipedia.org/wiki/Nuclear_fallout
Given how destructive neutron radiation is, I'm somewhat surprised that they'd be talking about strapping a reasonably strong source to someone's person.
Javascript + Nintendo DSi = DSiCade
The difficulty with small scale fusion isn't making it happen. That's been done many, many times. The difficulty with small scale fusion (and all fusion) is making it produce power (more power extracted from the reaction than put into the reaction).
That's where Pons and Fleishman got hosed. They claimed a 300% power surplus without experimental verification. This announcement is different from that for several reasons.
1) These guys are specifically not claiming excess power.
2) They're claiming to have lots of high-energy neutrons.
3) This is actually the announcement of a second group of scientists repeating the experiment and successfully verifying the results of the first group.
In short, this announcement is nothing like the cold fusion debacle of the late '80s.
Regards,
Ross
Indeed, it's different from all of those, read TFA. Here's a basic explanation of the device from RPI.
That is fusion. Moving neutrons from one atom to another increases the atomic weight of the recipient atom. You don't necessarily need to fuse atoms together to call something "fusion."
Wrong. Heat is random motion. If simple kinetic energy was all it took to have heat, then any gas cloud out in space with a large velocity relative to us would be extremely "hot." But we all know intuitively that things do not change temperature just because they speed up. The air in a moving car is not hotter than the air in a parked car. Heat is the random motion of particles with respect to each other. The collision of a few particles doesn't qualify.
When gas quickly depressurizes, it cools down. Ever wonder why? It's because as the gas escapes, the particles which are near each other tend to all move in the same direction (outward) and thus their random motions with respect to each other are decreased. Thus, the temperature drops. Or consider how a rocket nozzle works by focusing the molecular motions in a particular direction (by forcing the gas through a small opening to increase the pressure and then into a cone to suddenly decrease it), thereby converting the high pressure and heat of the exhaust gas into directed kinetic energy.
Learn more before making these kinds of proclamations.
And what are neutrons? Oh yeah, just one of the most penetrating and dangerous forms of radiation. Why else do you think that when they had to find a form of radiation that could kill tank crews inside their vehicles, the viable choice was the neutron bomb?
Pure fusion bombs create huge numbers of neutrons. If the explosion is near the ground, these neutrons can activate the debris that gets sucked into the mushroom cloud and create plenty of fallout. (Not to mention, most bombs use a natural uranium case to get a cheap energy boost when it's fissioned by the extra fusion neutrons. Most of total the energy output is often still fission.)
And any amount of emissions that's intense enough to kill cancer tumors isn't exactly "small".
Also: Nowhere in the article does it mention anything about breaking apart massive atoms and leaving behind radioactive isotopes that are chemically reactive in the human body; Which, I assume, is what you're so worried about.
Instead, you add neutrons to the the elements already inside your body, thereby turning them into dangerous radioactive isotopes where they sit.
Right you are.....
Although the figure is somewhat disputed by the US Customs, who claim they inspect a larger percentage of what they deem "high risk" containers, apparently about 2% of all containers entering the US are actually inspected (i.e. opened and the contents examined).
None of them can see the clouds; The polished wings don't care.
That's where Pons and Fleishman got hosed. They claimed a 300% power surplus without experimental verification.
I think the more important difference between this and Pons and Fleishman's cold fusion is that this is clearly fusion, and P&F wasn't. The effects P&F observed were probably the result of a chemical reaction and/or bad experimental design. They didn't observe any of the characteristic radiation or products.
FYI, this isn't the first tabletop deuterium fusion discovered. See bubble fusion.
If you can read this sig, you're too close.
I've never heard of deuterium fission. At the low end of the periodic table, it's far more energetically favorable for thing to fuse. I'm no expert, but D fission might even be endothermic.
You can think of their experiment like the classic Rutherford experiment, except they've got D+ ions being shot at a sheet of D. The two D+D fusion reactions happen with equal probability:
D + D -> T (1 MeV) + p (3 MeV)
D + D -> He3 (0.8 MeV) + n (2.5 MeV)
What they did in the experiment was to look for 2.5 MeV neutrons, because that reaction will _always_ produce a 2.5 MeV neutron. They also looked at associated X-rays. (If it was a fission neutron, it would probably be a different energy, and again, I can't find any reference to such a phenomenon.) Then they correlated their results to a computer simulation. I don't know why they didn't bother to look for the H and T. They may not have had the equipment, or they considered it outside the scope of the experiment's purpose as a neutron source.
The caveat to this experiment is that neutron and x-ray detection is something of an art, and must be done correctly; I'm not qualified to comment on their setup. This experiment makes sense according to normal physics, though.
You are arguing semantics. Within physics, it is only well defined within the field of statistical mechanics. Elsewhere it tends to be somewhat corrupted. People are always talking about the so-called "temperature" of particles in the interplanetary medium, even though they aren't even thermalized. Heat is thermal energy. If a group of particles isn't thermalized, they don't rightly have a temperature. If the temperature isn't well-defined (i.e. a non-equilibrium system, [i.e. a dynamic system]), then "heat" isn't well-defined either.
In this case, I am almost certain (without reading more than the first 5 paragraphs of the article) that the particles are not thermalized, are not, in fact, in equilibrium, and therefore do not have a temperature. In that case, you should assume right off the bat that if someone mentions words like "temperature", "heat", "hot", that they are referring to the kinetic energy of the particles, as that is the custom (at least within physics), and indeed, only interpretation that makes sense.
Furthermore, you miss the obvious point that there weren't even trying to make fusion. This should have been clear from the fact that when they said "room temperature" they meant that it was relatively hot and not cold (that is to say, not at cryogenic temperatures). The article is simply bad reporting by people that don't understand what they're talking about (unfortunately, not so uncommon).