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Nuclear Fusion Discovered
prostoalex writes "Both USA Today and The New York Times are reporting on research group from UCLA led by Seth J. Putterman which has discovered a form of nuclear fusion. The impact of the discovery? 'While the device is probably too inefficient to produce electricity or other forms of energy, the scientists say, egg-size fusion generators could someday find uses in spacecraft thrusters, medical treatments and scanners that search for bombs.' The findings are published in Nature magazine."
First of all, humans "discovered" fusion in 1953 with the first fusion bomb, or "hydrogen" bomb. What this speaks of is controlled fusion.
Secondly, this isn't fusion on even a battery scale; this is a few thousand atoms per second or so. So unfortunately, it's not a matter of scaling up to produce a reactor. The amount of energy being put into the system dwarfs by thousands of times the energy from fusion being put out.
Third, this isn't even the discovery of table-top laboratory scale fusion. As an undergraduate, I worked on a muon catalyzed fusion experiment at TRIUMF in Vancouver. By the time I was working on the experiment in 1994, the fusion reaction in the experiment was so well understood that it was being used to analyze other properties of solidified Hydrogen.
And I'm afraid it's a little bit of a dodge to say it's "at room temperature". The article doesn't say this, but presumably this takes place in a vaccum, where temperature is basically undefined in any conventional sense.
So a very nifty result, but not a discovery, I'm afraid. It will very likely be useful to study the fusion process, or perhaps other things as well.
Craig Steffen
http://www.craigsteffen.net
Anonymous Coward writes "Both Slashdot and Slashdot are reporting on the same story about the discovery of a form of nuclear fusion at UCLA. The impact of the dupe? 'While the dupe is probably too inefficient to produce new discussion or other forms of insight, the editors say, it could already find uses ad revenue creation through hundreds of comments about it being a dupe.' The findings are published in anti-slash.org."
Now if Slashdot could only fuse duplicate stories into one...
What a fool believes, he sees, no wise man has the power to reason away.
Heh. It's kind of a funny to watch us scientists who're interested in some particular natural phenonmenon to come up with the weirdest reasons why further research on the subject might help in the WAR AGAINST TERRORISM(!!1!one!).
No, actually it's not funny. It's sad.
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Terms, conditions and Homeland Security restrictions may apply.
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Can you really discover something twice on consecutive days???
;)
"My god, that discovery is even better than it was yesterday! I'm glad we discovered it again. Let's discover pepperoni pizza next!"
Only on Slashdot
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A UCLA collaboration (Seth Putterman, Brian Naranjo and Jim Gimzewski) appear to have developed a fusion device powered by a pyroelectric crystal, a type of crystal used in cell phones to filter signals. When heated, such a crystal produces a large electric charge on its surface. The UCLA researchers placed a lithium tantalate (LiTaO3) pyroelectric crystal so that one side touches a copper disc. A tiny tungsten probe is then placed at the center of the copper disc. When the crystal is subsequently heated, a very large large electric field is produced at the end of the tugsten tip, ~25 billion volts per meter. This field gradient is so high that it strips the electrons from nearby deuterium atoms. The ionized deuterium atoms then accelerated by this field towards a solid target of erbium deuteride (ErD2). They collide with it at such high energies that some fuse with the target. A measurement of almost 900 neutrons per second was observed. This is 400 times the background! Although the amount of energy produced in this initial experiment was miniscule (~1E-8 jules), this technology could be used for things like microthrusters. There are pictures and movies on the UCLA's physics site. Reader richmlpdx adds a link to coverage at MSNBC.
I would have thought that the editors would have gotten enough complaints about this being a dupe. Oh well.
:-/
What this device really is, is not so much of a fusion generator as it is a neutron source. Nuclear physicists use sources such as these for processes such as starting atomic reactions and changing elements. (e.g. You can make lead into gold with enough radiation. Although plutonium production is a far more useful change.)
A nuclear physicist I know suggested that the Sonofusion concept might be useful for the same reasons. Unfortuntely, we are quickly piling up ways of using fusion as neutron sources, but have yet to come up with a single one to produce energy.
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Obviously this discovery can also allow previously posted articles to Travel Through Time and appear a day later.
Wow.
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Why don't the /. administrators install some software that will help prevent these dupes from happening? For example, before allowing a /. admin to post an article, require a search of the past x days/weeks/months of /. posts and use document clustering to rank the top 5 or so most likely pages that are similar to the one about to be posted. Then before the /. poster makes his final decision, force him to look at the titles and summaries of those previous articles to make sure that he (or she..?) is not creating a dupe post. It's a simple and effective solution.
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That's fission. Fusion would lead to fewer dupes.
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
slashdot is a great site and a few dupes every now and then is NOT the end of the world as some spastic types would suggest
the only thing that puzzles me about dupes though is how it is possible that me, a very casual reader, is easily struck by their appearance, when an editor, supposedly editting their own website, fails to be struck by the duplication
i don't understand the mechanism by which that works
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
First of all, this is a dupe
Secondly, they haven't discovered fusion, they have invented a new type of fusion-based neutron generator. Several types of neutron generators are commonly known, and some are simple enough that you could build a working one in your garage. All of them use the same principle, more or less - high voltage, on the order of 100kV, accelerates deuterium ions into a deuterium (or tritium) containing target. So does this one.
The novelty is that they used a pyroelectric crystal to generate the high voltage. This makes the device small and self-contained, with no need for high-voltage electric machinery. All you do is heat-cycle the crystal with some 50 degree C temperature span, and you get fusion neutrons.
Note that like all fusion devices to date (other than bombs), this gadget produces a lot less fusion energy than is put in, and brings us no closer to having a fusion-based power source.
But it's a neat idea. And it makes a neat cheap laboratory neutron source.
It seems like somebody's discovering cold fusion just about every day now. .
The only acceptable defense of scientific results is to say that they were the product of the Scientific Method.
Fusion, time travel... Multiple posts. Cmon.
Thats what usually happens when they get Slashdot up to 88 miles per hour.
Where does the school board find them and why do they keep sending them to ME?
Given the state of the modern patent system...
After patenting fusion, would you try to license or sue:
God, for infringing on your patent, with "billions and billions" of offending instances?
Everyone else on Earth, for receiving the benefits of the unlicensed fusion source?
The living have better things to do than to continue hating the dead.
It took me a while to realize what the heck neutron sources might have to do with homeland security. I think what they have in mind is detection of fissile material (i.e. uranium and plutonium, as in nukes).
You irradiate the baggage/cargo (or whatever) with neutrons, and check the outgoing neutron flux with a geigerzahler or some other neutron detector. If there is fissile material in the baggage, some of it would split, generating detectably more neutrons.
If you want to get cute about it, note that fission neutrons have lower energy than fusion neutrons. Then use a neutron detector that can differentiate neutrons by energy.
Now, you can probably detect neutron flux from spontaneous fission without any irradiation, but depending on type of fissile material and amount of shielding that flux might be too low to detect reliably. And you wouldn't be able to tell an isotopic neutron source from fissile materials. Not that isotopic neutron sources shouldn't raise suspicion if found in cargo/baggage.
The only real problem with a detector based on neutron irradiation is that you have to keep people the hell away from it:-).
Who wants to be the first person who walks into a hospital A&E and tries to give a sensible excuse as to how one of those got lodged up his bottom?
Gentoo Linux - another day, another USE flag.
"Cold" fusion is when the nuclei fuse at "low" temperature. Not just the outside of the reactor that is cold, but the actual nuclei that fuse are "cold". When you're talking about the temperature of atoms, or nuclei, the temperature is the same as energy. This reactor accelerates the ions to high energy, so it's not "cold fusion".
The original "cold fusion" apparatus (the one that didn't work, or at least no one was ever able to replicate the experiment) used an electrolytic cell with palladium electrodes in an electrolyte. Nowhere in the apparatus were the deuterium nuclei accelerated to high speed. The theory was that the current somehow induces the deuterium to infuse into the palladium electrode, where the deuterium nuclei get close enough to each other to fuse, without you having to clash them together at high energy.
That was the cool thing about it (pardon the pun). You didn't have to put much energy into the system, so you had more energy coming out than you had to put in, making it a feasable power source. If it worked:-).
They're not claiming it's self-sustaining. They're just claiming that it's novel, which it is, and that it's a neutron generator, which it is.
A commentary article in the current journal of Nature points out that "...portable neutron generators have found a wide range of applications, including welllogging for oil exploration, and the screening of baggage for airline security," but that "high-voltage power is required, and the apparatus is fairly complex."
This device is much simpler and more straightforward.
Third, this isn't even the discovery of table-top laboratory scale fusion.
True, but it is probably one of the simplest and most compact fusion/neutron generating techniques invented to date.
And I'm afraid it's a little bit of a dodge to say it's "at room temperature". The article doesn't say this, but presumably this takes place in a vaccum, where temperature is basically undefined in any conventional sense.
Please RTFA before you critique it. This method uses a pyroelectric crystal, heated presumably up to 100-200 Celsius or so, and a thin deuterium gas and a target made of erbium deuteride, both of which are presumably at or near room temperatures.
In any case, by "cold" fusion we typically mean "at temperatures easily maintainable in a lab," to distinguish from "hot" fusion which occurs at many thousands or millions of degrees.
Also, you should know that even in a "perfect" vacuum, temperature is and can be well-defined, usually by thermal radiation equilibrium with the enclosure. Even outer space has a well-defined thermal radiation background, which I think is within a couple degrees of absolute zero.
Their setup: The 'crystal' mentioned in the mainstream articles, is a z-cut lithium tantalate crystal (LiTaO3), with the negative axis facing outward onto a hollow copper block. A tiny tungsten probe (80 microns long and 100 nm wide) is then attached to the other crystal face. This probe acts as a tiny mast for the electric field so that there is a powerful electrical field at the tip of the probe. Then there were a bunch of fancy neutron-counters and single-photon counters bundled around it.
What they did: First they added deuterium gas (at 0.7 Pa) and then cooled the crystal down using liquid nitrogen (to 240 K). Then they used a little heater to increase the chamber temperature slowly.
What happened: Less than 3 minutes later, and still below 273 K (0 degrees Celcius), the neutron signal rose above the background level. There were x-rays coming from the probe tip, and a whole bunch of neutrons. After a few more minutes, the electric field was so strong that it caused arcing between the probe tip and the enclosure (because they kept heatingthe crystal, and the field thus kept getting stronger). The arcing stopped the process (and I'd guess it damages the crystal?).
They added a few links in the article to previous papers: a pdf describing the concept they are trying to harness, another pdf with more about how they use the crystals with the deuterium gas, and a brief abstract.
I think this is pretty cool. I bet/hope that before long (within 10 years), this will be powering small extrasolar probes.
Pretty neat stuff. I don't even mind dupe posts when they're on such important stuff.
Yes, it's only about creating a controlled stream of neutrons, with a device the size of a toaster. It's a good step forward for that though.
aparatus for identifying unknown substances non-invasively can now be made cheaper and more portable.
Make it smaller still, and perhaps you could swallow a radiation source to treat bowell cancer on the way through, instead of irradiating your whole body from the outside.
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