Posted on 04/28/2005 11:22:26 AM PDT by ckilmer
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April 28, 2005 Itty-Bitty and Shrinking, Fusion Device Has Big Ideas By KENNETH CHANG
n a surprising feat of miniaturization, scientists are reporting today that they have produced nuclear fusion - the same process that powers the sun - in a footlong cylinder just five inches in diameter. And they say they will soon be able to make the device even smaller.
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, by a team at the University of California, Los Angeles, led by Dr. Seth J. Putterman, are being reported in the journal Nature.
The minifusion device accelerates hydrogen atoms and slams them together to produce helium. Unlike earlier claims of tabletop fusion - "cold fusion," in 1989, which suggested that energy could be produced by running electricity through water and metal plates, and "sonofusion," in 2002, in which collapsing bubbles supposedly heat gases to starlike temperatures - this report is not being greeted with skepticism.
"I think it's very persuasive," said Dr. William Happer, a professor of physics at Princeton.
Dr. Michael J. Saltmarsh, a retired scientist who worked at Oak Ridge National Laboratory in Tennessee, said the energy of the particles emitted by the collisions convincingly matched what was expected for fusion. Dr. Saltmarsh was one of two Oak Ridge scientists who said they were unable to detect the signatures of fusion in the 2002 sonofusion experiment.
In a commentary accompanying the Nature paper, Dr. Saltmarsh described the new device as "intriguingly simple" and added, "Indeed, in some ways it is remarkably low tech."
By contrast with the earlier claims, the U.C.L.A. researchers do not assert that their invention will provide unlimited energy. "What we've built so far," Dr. Putterman said, "no chance."
Indeed, the new device does not even produce enough energy to warm the hand. But it could be useful as a source of neutrons, the subatomic particles that are a byproduct of fusion. Because neutrons do not have any electrical charge, they can penetrate deep into matter, and that could provide a way to peer easily into luggage or cargo containers.
"We can give them a little tiny front end for a camera that can look behind things," Dr. Putterman said.
The central component of the device is a crystal of lithium tantalate, which belongs to a class of materials known as pyroelectrics. Pyroelectrics, which generate strong electric fields when heated or cooled, have long been known, possibly described as far back as 314 B.C. by a student of Aristotle.
"It's quite a surprise to see it used in this way," Dr. Happer of Princeton said.
In the experiment, the crystal, a cylinder about an inch and a quarter in diameter and a half-inch in length, was mounted inside the footlong cylinder and surrounded by a gas of deuterium, a heavy version of hydrogen. Warming the crystal about 50 degrees Fahrenheit produced a charge of 1,000 volts. That created electric fields around a tungsten tip that were so strong that they ripped electrons off the deuterium and accelerated the charged deuterium ions into a target that also contained deuterium.
When one deuterium ion hit a deuterium atom, fusion occurred. Sometimes. But because only one in a million of the collisions actually produce fusion, the device is an inefficient generator of energy.
The jet of deuterium ions could serve as thrusters for small spacecraft, and X-rays produced by electrons' being caught in the powerful electric fields might be useful for treating tumors.
The current device produces only about 1,000 neutrons a second, few enough that it would not be dangerous to use even in a physics demonstration, Dr. Saltmarsh said. The researchers plan a more powerful version by replacing deuterium in the target with tritium, an even heavier form of hydrogen, generating about 250 times as many neutrons. Additional improvements should raise the rate to a million neutrons a second.
Commercial neutron generators, which can already make a million neutrons a second, similarly accelerate deuterium into targets, but they rely on high-voltage power sources to generate the electric fields.
By relying on pyroelectric crystals instead, the U.C.L.A. research could lead to generators that are much simpler and less expensive.
"What Putterman's made is an amazing little accelerator," Dr. Happer said. "It's a version of that that doesn't need any high voltage."
Dr. Putterman says he envisions a device consisting just of an egg-size container with a crystal, deuterium gas and the target inside. Plunging the container into ice water or warming it with body heat would be enough to set off the reactions. "We can diddle temperature a mere 30 degrees and generate fields that make fusion," he said.
Seems ACME was marketing something like that too.
Controlled Fusion isn't the problem or the goal.
We need controlled fusion that is a net producer of energy rather than a consumer of it.
So9
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none of the four types of fusion reactions I've seen in the last couple years are net producers of energy except for cold fusion. while the DOE has been saying positive stuff about it of late, cold fusion is still seen to be the least likely of the bunch to make the grade. But who knows. the real news these days is happening on the scientific and technological front. where anything can happen.
("There is not the slightest indication that nuclear energy will ever be attainable"- Albert Einstein)
an excellent album. tied for my favorite of his, with Kind of Blue.
I looked around for some info on that ITER project yesterday after I posted that article, and it seems that the final agreement is all but settled. The reactor will be in France, with Japan as a "privileged partner" in management and research contracts. The EU basically issued an ultimatum that they would go ahead regardless if final agreement weren't nailed down by this July. All that's left now is to hammer out the exact details of the the "privileged" partnership. (We're just one of the red-headed steppartners, who gets to pony up cash and hope something comes of it).
Actually, I don't believe we have heard the end of the so-called "cold fusion" (deuterium-paladium).
Physicists in the US have generated nuclear fusion in a simple, table-top device operating at room temperature. The device, built by Brian Naranjo, Jim Gimzewski and Seth Putterman at the University of California at Los Angeles (UCLA), causes two deuterium nuclei to collide with each other and generate alpha particles, neutrons and energy (Nature 434 1115). The device could have applications as a portable neutron generator or in the propulsion systems for miniature spacecraft, but will not be useful as an energy source because it consumes more energy than it produces.
The experimental set-up consists of a centimetre-sized cylindrical crystal of lithium tantalate (LiTaO) surrounded by deuterium gas. This material is pryoelectric, which means that positive and negative charges build up on opposite faces of the crystal when it is heated. This creates an electric field that is high enough to ionize any deuterium atoms that stray near a tiny tungsten tip attached to the positively charged surface. These deuterium ions get repelled from the surface and are accelerated by the field towards an erbium deuteride target, where the fusion reactions take place.
The device currently emits about 900 neutrons every second, and the UCLA team say that it could be used as a "simple palm-sized neutron generator" if the output can be increased to about one million neutrons per second. Using tritium rather than deuterium in the target will increase the neutron yield by a factor of 250, says Naranjo, and optimizing the geometry and increasing the beam current should provide another factor of four.
"What they have made is a cute little neutron generator," says Michael Saltmarsh, a physicist who has retired from the Oak Ridge National Laboratory in the US. "You can imagine having one of those in your pocket but don't get it too warm! However, the neutron intensity is still much lower than you can get from commercially available neutron generators."
Putterman and co-workers at UCLA are also involved in efforts to generate fusion reactions in "sonoluminescence" experiments in which bubbles in a liquid are forced to expand and contract by sound waves. In 2002 Rusi Taleyarkhan of Oak Ridge and colleagues reported that they had observed "bubble fusion" in experiments with deuterated acetone. The report was greeted with skepticism by other researchers in the field, including the UCLA group, who were unable to reproduce the results. However, the Defense Advanced Research Projects Agency (DARPA) in the US has recently funded Taleyarkhan, who is now at Purdue University, and Putterman to collaborate and exchange information on bubble fusion.
Ling to news release and abstract in Nature.
http://www.nature.com/news/2005/050425/full/050425-3.html#B1
yeah, you're right.
I'm of the uninformed opinion that nothing will come of that project just because its too big.
there's something esthetically wrong about looking for a way to cut costs with something big and costly.
but my arguement is merely to do with esthetics.
maybe too I like the idea of power streaming in from many cheap portable sources rather than one really big cheap source.
The Manhattan Project employed some 10,000 scientists at its peak and cost $24 billion in 2005 dollars..
Well, OF COURSE you can pull this off if you use a crystal of lithium tantalate. Hasn't the challenge always been to do with WITHOUT lithimum tantalate??? Now THAT would be impressive!
mark
Some may laugh, but this looks very much like "Beam Power Tubes" of old, complete with a grid and beam forming screen with heat as a catalyst instead of high voltage. Enlighten me FReepers.
i did a little googling of neutron production and found that there are devices out there that will produce neutrons if that's what your interested in doing.
but I don't really understand the subject sufficiently to have much more to say on it.
"Didn't Uncle Rico use some of his sweet moolah to buy one of these things off of the internet? He's still walking funny..."
Gratuitous Napoleon Dynamite reference?
The Manhattan Project employed some 10,000 scientists at its peak and cost $24 billion in 2005 dollars..
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If that's the case then the US government still doesn't understand the urgency of the situation. If urgency is measured in dollars spent to solve a problem.
You could use it to run the Googleplex Hz processor, with Terrabytes of RAM, and the refrigeration unit to cool them.
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