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Posts: 131433
RE: Fusion device

A Purdue University committee reviewing issues concerning the "bubble fusion" research by one of its professors said yesterday that it has completed its work, but it will not make public the investigation recommendations, including any possible disciplinary action.


Purdue University has finished a review into the methods of a researcher who claimed to have created bubble fusion using a tabletop device.
For those hoping to find answers in the strange saga, disappointment may be the only reward at the end of the three-month wait.
Purdue launched a review of the work of Rusi Taleyarkhan after an article published in the science journal Nature cast doubt on his ability to produce the complicated reaction under the circumstances he described.


-- Edited by Blobrana at 01:52, 2006-07-25



Posts: 131433

Physicist Rusi Taleyarkhan of Purdue University in West Lafayette, Indiana, published the first evidence of 'sonofusion' in 2002; he has been dogged by sceptics ever since.

The underlying physics behind the idea is valid, according to Ken Suslick. An expert in sonoluminescence at the University of Illinois in Urbana-Champaign, Suslick tried and failed to replicate Taleyarkhan's first results. If the bubbles' collapse is sufficiently intense, it should indeed be able to crush atoms together.

Taleyarkhan's first experiments were conducted while he was based at Oak Ridge National Laboratory in Tennessee. His idea was to use liquid acetone in which hydrogen atoms had been replaced by their heavier brethren, deuterium. When deuterium nuclei fuse together, they emit a characteristic burst of neutrons. But critics pointed out that Taleyarkhan was using an external source of neutrons to 'seed' the bubbles, and that these were swamping his measurements of neutrons produced by the fusion reaction itself.

"This time round there are no external neutrons. In this experiment we use three independent neutron detectors and a gamma-ray detector" - Rusi Taleyarkhan.

Instead, his team loaded a mixture of deuterated acetone and benzene with a uranium salt. As the uranium undergoes radioactive decay it releases alpha particles, which can also seed bubble formation.
The results from the four instruments prove that fusion is happening inside his experiment, asserts Taleyarkhan.
Although uranium can release neutrons during fission reactions, Taleyarkhan rules them out because the neutrons he finds bear the energetic hallmark of having come from the fusion of two deuterium nuclei.
Taleyarkhan's test reactor still puts out a lot less energy than it takes in, making it impractical for generating power.

The results of the new experiment are to be published in Physical Review Letters in a few weeks' time.

There is one big problem, however: the experiment doesn't always work, and the group is not sure why. Seth Putterman, a physicist at the University of California, Los Angeles, who has also tried to verify some of Taleyarkhan's experiments, notes that the paper does not reveal how many failed runs were required before the team saw a trace of fusion neutrons.
Putterman notes that the team did not continuously monitor background neutron levels. Although the neutron count doubles at some points in the experiments, Putterman says that neutrons produced in random showers of cosmic rays, rather than fusion events, could be responsible. But Taleyarkhan points out that the neutron count was smaller in detectors further from the reaction chamber.

To prove that the neutrons are coming from fusion as bubbles burst, Putterman and Suslick suggest that the team closely monitor exactly when the neutrons appear. The current experiment simply counts up the number of neutrons detected over minutes, so correlations with bubble bursts cannot be seen.
Another obvious way to confirm that fusion is happening would be to look for tritium, a heavier isotope of hydrogen produced by fusion reactions. Tritium leaves a telltale signature of high-energy electrons when it decays and Taleyarkhan claimed to see this in similar previous experiments. But in the current tests, tritium's signature is overwhelmed by beta-decay from the uranium, making it impossible to spot.

-- Edited by Blobrana at 05:51, 2006-01-12



Posts: 131433

Laser physicists in Europe have put forward plans to build a £500m facility to study a new approach to laser fusion. A panel of scientists from seven European Union countries believes that a "fast ignition" laser facility could make a significant contribution to fusion research, as well as supporting experiments in other areas of physics. The facility could be up and running by the middle of the next decade.

The laser would be used to compress and heat a small capsule of deuterium and tritium until the nuclei are hot enough to undergo nuclear fusion and produce helium and neutrons. In a reactor the energy of the neutrons would be used to generate electricity without the emission of greenhouse gases or the generation of long-lived nuclear waste.

The most advanced approach to fusion involves using magnetic fields to confine the deuterium–tritium plasma. This is the route to be taken by ITER, which will cost $10bn to build and run. The alternative "inertial confinement" technique, which uses lasers or ion beams rather than magnets to confine the plasma, will be investigated by the National Ignition Facility (NIF) in the US and the Laser Mégajoule (LMJ) in France. However, both these billion-dollar lasers will primarily be used for nuclear-weapons research, with only 15% of their time being available for other areas of physics.

In the conventional approach to inertial confinement, which will be used at NIF and LMJ, the lasers that compress the fuel capsule also heat it. Fast ignition, which was first proposed by Max Tabak of the Lawrence Livermore National Laboratory in the US, relies on different lasers for these two stages. According to Henry Hutchinson of the Rutherford Appleton Laboratory in the UK, who set up the European panel, fast ignition requires less laser energy than the conventional approach, which means that it is considerably cheaper.

"The energy problem is sufficiently urgent that we cannot afford to ignore different approaches to fusion," he says. Hutchinson also stresses that any fast-ignition laser would be a civilian facility, and would be available for research on astrophysics, atomic physics and nuclear physics as well.

Fast ignition was first demonstrated at the Gekko XII laser at Osaka University in Japan in 2001, working with a team of UK scientists. Kodama and colleagues are now upgrading their laser system in order to approach "breakeven" - the point at which the energy output is equal to the energy needed to sustain the reaction. They then plan to further enhance their system so that it reaches ignition, which happens when the fusion reactions generate enough energy to sustain themselves without the need for further heating. Finally, they hope to build a demonstration fast-ignition facility. Physicists in the US are also studying fast ignition.

HiPER, as the European proposal is provisionally known, would be designed to achieve high energy gains, providing the critical intermediate step between ignition and a demonstration reactor. It would consist of a long-pulse laser with an energy of 200 kJ to compress the fuel and a short-pulse laser with an energy of 70 kJ to heat it.

If Hutchinson and colleagues can persuade research councils across Europe to back the proposal, construction could start around the end of the decade. Although the panel's report does not discuss where the laser should be built, the UK would be a contender to host the facility.




Posts: 131433
RE: Fusion device

Russian scientists have managed to use lasers to create a billion-degree nuclear fireball. The resulting fusion reaction is far cleaner than the kind currently being investigated to generate nuclear power.

Sadly, the team's efforts are no good for power generation at the moment as the laser takes so much energy to run. But achieving this kind of laser-driven fusion in the lab will give scientists a better way to investigate the phenomenon, which could one day be used to create cleaner energy.

Currently, the main contender for generating fusion power uses strong magnetic fields to confine a fiery plasma of atomic nuclei: fusion experts hope that the International Thermonuclear Experimental Reactor (ITER), to be built in Cadarache, France, will fuse deuterium and tritium nuclei together in this way to create energy.

But this reaction also produces copious amounts of neutrons. When these neutrons hit the reactor walls they generate radioactive isotopes that will eventually have to be disposed of. And although this radioactive waste is cleaner than the by-products created by fission, the reaction used by today's nuclear power plants, it isn't perfect.

So some physicists have suggested using a different fusion process instead, which forces protons and boron nuclei together in a reaction that generates virtually no neutrons.

Although this sounds safer, kick-starting proton-boron fusion requires temperatures of a billion degrees, more than ten times the heat needed by the deuterium-tritium reaction.
"Deuterium-tritium fusion is the reaction of choice simply because it's easier to achieve" - Gennady Shvets, a physicist at the University of Texas at Austin.

Now a team of Russian scientists have topped the billion-degree mark in a system that does not need huge magnets to confine the reaction.
"We have achieved a neutronless proton-boron reaction for the first time using a laser" - Vadim Belyaev, physicist from the Central Research Institute of Machine Building, Koralev, Russia.

The team blasted polythene pellets containing boron atoms with laser pulses that last for just over a trillionth of a second (10^-12 seconds). This creates an intensely hot plasma where protons from the polythene merge into boron atoms, which then fall apart to release a stream of helium nuclei, also known as alpha particles.

Lumbering alpha particles tend to stay within the reaction mixture rather than escaping to make surrounding equipment radioactive. Crucially, the team detected no neutrons coming from the reaction at all.

The success opens the door to "an ecologically pure technology of nuclear energy production", says Belyaev, whose team reports its research in the journal Physical Review E.

An added advantage to the system is that the charged alpha particles could be directly tapped as a source of electric current. A power plant based on ITER would simply use the heat from fusion to turn electrical turbines, much as coal-fired power stations do today.

And laser-driven fusion might be easier to sustain than the reaction inside magnetic bottles used by projects such as ITER. In theory, once the reaction is going, all one would have to do is keep dropping fuel pellets into the beam. In contrast, ITER will use giant magnets to keep a turbulent, burning ball of plasma confined. "Unfortunately (confinement) is the least understood process in fusion" - Gennady Shvets.

Other labs, including the National Ignition Facility at Lawrence Livermore National Laboratory in California, similarly use lasers to investigate fusion, but of the dirtier deuterium-tritium type. Belyaev now hopes to see a wider international project to investigate the proton-boron reaction.




Posts: 131433
RE: Sonoluminescence

Researchers at Purdue University have new evidence supporting earlier findings by other scientists who designed an inexpensive "tabletop" device that uses sound waves to produce nuclear fusion reactions.
The technology, in theory, could lead to a new source of clean energy and a host of portable detectors and other applications.
The new findings were detailed in a peer-reviewed paper appearing in the May issue of the journal Nuclear Engineering and Design.
The paper was written by Yiban Xu, a post-doctoral research associate in the School of Nuclear Engineering, and Adam Butt, a graduate research assistant in both nuclear engineering and the School of Aeronautics and Astronautics.
A key component of the experiment was a glass test chamber about the size of two coffee mugs filled with a liquid called deuterated acetone, which contains a form of hydrogen known as deuterium, or heavy hydrogen. The researchers exposed the test chamber to subatomic particles called neutrons and then bombarded the liquid with a specific frequency of ultrasound, which caused cavities to form into tiny bubbles. The bubbles then expanded to a much larger size before imploding, apparently with enough force to cause thermonuclear fusion reactions.
Fusion reactions emit neutrons that fall within a specific energy range of 2.5 mega-electron volts, which was the level of energy seen in neutrons produced in the experiment. The experiments also yielded a radioactive material called tritium, which is another product of fusion, Xu and Butt said.
The Purdue research began two years ago, and the findings represent the first confirmation of findings reported earlier by Rusi Taleyarkhan. Now at Purdue, Taleyarkhan, the Arden L. Bement Jr. Professor of Nuclear Engineering, discovered the fusion phenomenon while he was a scientist working at the Oak Ridge National Laboratory.

"The two key signatures for a fusion reaction are emission of neutrons in the range of 2.5 MeV and production of tritium, both of which were seen in these experiments" - Yiban Xu.

The same results were not seen when the researchers ran control experiments with normal acetone, providing statistically significant evidence for the existence of fusion reactions.

"The control experiments didn't show anything. We changed just one parameter, substituting the deuterated acetone with normal acetone" - Yiban Xu.

Deuterium contains one proton and one neutron in its nucleus. Normal hydrogen contains only one proton in its nucleus.
Taleyarkhan led a research team that first reported the phenomenon in a 2002 paper published in the journal Science. Those researchers later conducted additional research at the Oak Ridge National Laboratory, Rensselaer Polytechnic Institute and the Russian Academy of Sciences and wrote a follow-up paper that appeared in the journal Physical Review E in 2004, just after Taleyarkhan had come to Purdue.
Scientists have long known that high-frequency sound waves cause the formation of cavities and bubbles in liquid, a process known as "acoustic cavitation," and that those cavities then implode, producing high temperatures and light in a phenomenon called "sonoluminescence."

In the Purdue research, however, the liquid was "seeded" with neutrons before it was bombarded with sound waves. Some of the bubbles created in the process were perfectly spherical, and they imploded with greater force than irregular bubbles. The research yielded evidence that only spherical bubbles implode with a force great enough to cause deuterium atoms to fuse together, similar to the way in which hydrogen atoms fuse in stars to create the thermonuclear furnaces that make stars shine.
Nuclear fusion reactors have historically required large, expensive machines, but acoustic cavitation devices might be built for a fraction of the cost. Researchers have estimated that temperatures inside the imploding bubbles reach 10 million degrees Celsius and pressures comparable to 1,000 million earth atmospheres at sea level.
Xu and Butt now work in Taleyarkhan's lab, but all of the research on which the new paper is based was conducted before they joined the lab, and the research began at Purdue before Taleyarkhan had become a Purdue faculty member.

The two researchers used an identical "carbon copy" of the original test chamber designed by Taleyarkhan, and they worked under the sponsorship and direction of Lefteri Tsoukalas, head of the School of Nuclear Engineering.
Although the test chamber was identical to Taleyarkhan's original experiment, and the Purdue researchers were careful to use deuterated acetone, they derived the neutrons from a less-expensive source than the Oak Ridge researchers.
The scientists working at Oak Ridge seeded the cavities with a "pulse neutron generator," an apparatus that emits rapid pulses of neutrons. Xu and Butt derived neutrons from a radioactive material that constantly emits neutrons, and they simply exposed the test chamber to the material.
Development of a low-cost thermonuclear fusion generator would offer the potential for a new, relatively safe and low-polluting energy source. Whereas conventional nuclear fission reactors make waste products that take thousands of years to decay, the waste products from fusion plants would be short-lived, decaying to non-dangerous levels in a decade or two. For the same unit mass of fuel, a fusion power plant would produce 10 times more energy than a fission reactor, and because deuterium is contained in seawater, a fusion reactor's fuel supply would be virtually infinite. A cubic kilometre of seawater would contain enough heavy hydrogen to provide a thousand years' worth of power for the United States.
Such a technology also could result in a new class of low-cost, compact detectors for security applications that use neutrons to probe the contents of suitcases; devices for research that use neutrons to analyze the molecular structures of materials; machines that cheaply manufacture new synthetic materials and efficiently produce tritium, which is used for numerous applications ranging from medical imaging to watch dials; and a new technique to study various phenomena in cosmology, including the workings of neutron stars and black holes.

The desktop experiment is safe because, although the reactions generate extremely high pressures and temperatures, those extreme conditions exist only in small regions of the liquid in the container – within the collapsing bubbles.
Purdue researchers plan to release additional data from related experiments in October during the Nuclear Reactor Thermal Hydraulics conference in Avignon, France.

The 2004 paper was written by Taleyarkhan while a distinguished scientist at Oak Ridge National Laboratory, postdoctoral fellow J.S Cho at Oak Ridge Associated Universities; Colin West, a retired scientist from Oak Ridge; Richard T. Lahey Jr., the Edward E. Hood Professor of Engineering at Rensselaer Polytechnic Institute (RPI); R.C. Nigmatulin, a visiting scholar at RPI and president of the Russian Academy of Sciences' Bashkortonstan branch; and Robert C. Block, active professor emeritus in the School of Engineering at RPI and director of RPI's Gaerttner Linear Accelerator Laboratory.




Posts: 131433
RE: Fusion device

how about a bit of DIY?

"Sonofusion" generates nuclear reactions by creating tiny bubbles that implode with tremendous force.
The original researchers produced tritium; and there is only one way to produce tritium – through nuclear processes
The findings were reported in a paper that appeared in the journal Physical Review E, published by the American Physical Society.

The discovery was first reported in March 2002 in the journal Science.
Since then the researchers have acquired additional funding from the U.S. Defence Advanced Research Projects Agency, purchased more precise instruments and equipment to collect more accurate data, and successfully reproduced and improved upon the original experiment.
A fair amount of very substantial new work was conducted and also, this time top scientists and physicists from around the world and experts in neutron science came to the lab to review the procedures and findings before the manuscript was submitted to a journal.

The device is a clear glass canister about the height of two coffee mugs stacked on top of one another. Inside the canister is a liquid called deuterated acetone (C3D6O). The acetone contains a form of hydrogen called deuterium, or heavy hydrogen, which contains one proton and one neutron in its nucleus.
Normal hydrogen contains only one proton in its nucleus.
The researchers expose the clear canister of liquid to pulses of neutrons every five milliseconds, or thousandths of a second, causing tiny cavities to form.
At the same time, the liquid is bombarded with a specific frequency of ultrasound, which causes the cavities to form into bubbles that are about 60 nanometres – or billionths of a meter – in diameter.
The bubbles then expand to a much larger size, about 6,000 microns, or millionths of a metre – large enough to be seen with the unaided eye.
The process is analogous to stretching a slingshot from Earth to the nearest star, our sun, thereby building up a huge amount of energy when released.
Within nanoseconds these large bubbles contract with tremendous force, returning to roughly their original size, and release flashes of light in a well-known phenomenon known as sonoluminescence..

Because the bubbles grow to such a relatively large size before they implode, their contraction causes extreme temperatures and pressures comparable to those found in the interiors of stars. Researches estimate that temperatures inside the imploding bubbles reach 10 million degrees Celsius and pressures comparable to 1,000 million earth atmospheres at sea level.

At that point, deuterium atoms fuse together, the same way hydrogen atoms fuse in stars, releasing neutrons and energy in the process.
The process also releases a type of radiation called gamma rays and a radioactive material called tritium, all of which have been recorded and measured by the team. In future versions of the experiment, the tritium produced might then be used as a fuel to drive energy-producing reactions in which it fuses with deuterium.
Whereas conventional nuclear fission reactors produce waste products that take thousands of years to decay, the waste products from fusion plants are short-lived, decaying to non-dangerous levels in a decade or two.

The desktop experiment is safe because, although the reactions generate extremely high pressures and temperatures, those extreme conditions exist only in small regions of the liquid in the container – within the collapsing bubbles.
One key to the process is the large difference between the original size of the bubbles and their expanded size. Going from 60 nanometres to 6,000 microns is about 100,000 times larger, compared to the bubbles usually formed in sonoluminescence, which grow only about 10 times larger before they implode.
This means you've got about a trillion times more energy potentially available for compression of the bubbles than you have with conventional sonoluminescence.
When the light flashes are emitted, it's getting extremely hot, and if your liquid has deuterium atoms compared to ordinary hydrogen atoms, the conditions are hot enough to produce nuclear fusion.
The ultrasound switches on and off about 20,000 times a second as neutrons are bombarding the liquid.
Each five-millisecond pulse of neutrons is followed by a five-millisecond gap, during which time the bubbles implode, release light and emits a surge of about 1 million neutrons per second.

In the first experiments carried out, with the less sophisticated equipment, the team was only able to collect data during a small portion of the five-millisecond intervals between neutron pulses. The new equipment enabled the researchers to see what was happening over the entire course of the experiment.
The data clearly show surges in neutrons emitted in precise timing with the light flashes, meaning the neutron emissions are produced by the collapsing bubbles responsible for the flashes of light.

Neutrons are emitted each time the bubble is implodes with sufficient violence.
Fusion of deuterium atoms emits neutrons that fall within a specific energy range of 2.5 mega-electron volts or below, which was the level of energy seen in neutrons produced in the experiment.
The production of tritium also can only be attributed to fusion, and it was never observed in any of the control experiments in which normal acetone was used.
Whereas data from the previous experiment had roughly a one in 100 chance of being attributed to some phenomena other than nuclear fusion, the new, more precise results represent more like a one in a trillion chance of being wrong.

(adapted from source)

Using concentrated sulphuric acid as the medium subjected to acoustic treatment, a pair of scientists, David J. Flannigan and Dr Kenneth Suslick, have obtained the most intense sonoluminescence yet seen. With this spectral information they confirm that temperatures reach as high as 15,000 K, and thus indicate that the collapsed bubble has a hot plasma core.

Impulse Devices, a developer of sonofusion power (acoustic inertial confinement fusion, AICF), announced on Dec 14th 2004, the availability of its research reactor to laboratories, universities, power equipment manufacturers and utilities attempting to produce a new alternative energy.

The IDI reactor is a stainless steel sphere filled with heavy water and, at its centre, a small bubble of deuterium (heavy hydrogen). The IDI research reactor has a diameter of 1 foot and costs $250,000 with custom input-output systems and instrumentation.


-- Edited by Blobrana at 19:04, 2005-06-09



Posts: 131433
RE: Cold Fusion

Windoze Media stream (from April 28th 2005)

(copy URL link into your player)

-- Edited by Blobrana at 22:47, 2005-06-07



Posts: 131433
RE: Cold Fusion device

(old news)

A very reputable, very careful group of scientists at the University of Los Angeles (Brian Naranjo, Jim Gimzewski, Seth Putterman) has initiated a fusion reaction using a laboratory device that's not much bigger than a breadbox, and works at roughly room temperature. This time, it looks like the real thing.

Before going into their specific experiment, it's probably a good idea to define exactly what nuclear fusion is, and why we're so interested in understanding the process. This also gives me an excuse to talk about how things work deep inside the nuclei of atoms, a topic near and dear to most astronomers (more on that later).

Simply put, nuclear fusion means ramming protons and neutrons together so hard that they stick, and form a single, larger nucleus. When this happens with small nuclei (like hydrogen, which has only one proton or helium, which has two), you get a lot of energy out of the reaction. This specific reaction, fusing two hydrogen nuclei together to get helium, famously powers our sun (good), as well as hydrogen bombs (bad).

Fusion is a tremendous source of energy; the reason we're not using it to meet our everyday energy needs is that it's very hard to get a fusion reaction going. The reason is simple: protons don't want to get close to other protons.

Do you remember learning about electricity in high school? I sure do - I dreaded it whenever that topic came around. I had a series of well-meaning science teachers that thought it would be fun for everyone to hold hands and feel a mild electric shock pass their arms. Every time my fists clenched and jerked and I had nothing consciously do with it, my stomach turned.

In addition, I have long, fine hair, and was often made a victim of the Van de Graf generator - the little metal ball with a rubber belt inside it that creates enough static electricity to make your hair stand on end. Yeesh.

Anyway, hopefully you remember the lesson that two objects having different electrical charges (positive and negative) attract one another, while those with the same charge repel. It's a basic law of electricity, and it definitely holds true when two protons try to get close together. Protons have positive charges, and they repel each other. Somehow, in order for fusion to work, you've got to overcome this repulsive electrical force and get the things to stick together.

Here's where an amazing and mysterious force comes in that, although we don't think about it in our day-to-day lives, literally holds our matter together. There are four universal forces of nature, two of which you're probably familiar with: gravity and electromagnetism.

But there are two other forces that really only come in to play inside atomic nuclei: the strong and weak nuclear forces (and yes, the strong force is the stronger of the two, the weak is weaker. Scientists really have a way with names, dont they?) I'm going to focus on the strong force, as that's the one responsible for nuclear fusion.

The strong force is an attractive force between protons and neutrons - it wants to stick them together. If the strong force had its way, the entire universe would be one big super-dense ball of protons and neutrons, one big atomic nucleus, in fact.

Fortunately, the strong force only becomes strong at very small scales: about one millionth billionth of a meter. Yes, that's 0.000000000000001 meters. Any farther away, and the strong force loses its grip. But if you can get protons and neutrons that close together, the strong force becomes stronger than any other force in nature, including electricity.

That's important- all protons have the same charge, so they'd like to fly away from each other. But if you can get them close together, inside the volume of an atomic nucleus, the strong force will bind them together.

The whole trick with fusion is you've got to get protons close enough together for the strong force to overcome their electrical repulsion and merge them together into a nucleus. The sun does this pretty much by brute force. The sun has over 300,000 times the mass of the Earth, which means there's a lot of gravity weighing down on its core.

That pressure gets the sun's internal temperature up to several millions of degrees, which means that particles inside the sun's core are flying around at huge velocities. Everything is moving around so fast that protons sometimes get slammed together before their charges have a chance to repel. The strong force takes hold, and a new atom (helium) is born.

In this process, some of the mass of the protons is converted into energy, powering the sun and producing the light that will eventually reach the Earth as sunlight.

Scientists have gotten fusion to occur in the laboratory before, but for the most part, they've tried to mimic conditions inside the sun by whipping hydrogen gas up to extreme temperatures or slamming atoms together in particle accelerators. Both of those options require huge energies and gigantic equipment, not the sort of stuff easily available to build a generator. Is there any way of getting protons close enough together for fusion to occur that doesnt require the energy output of a large city to make it happen?

The answer, it turns out, is yes.

Instead of using high temperatures and incredible densities to ram protons together, the scientists at UCLA cleverly used the structure of an unusual crystal.

Crystals are fascinating things; the atoms inside are all lined up in a tightly ordered lattice, which creates the beautiful structure we associate with crystals. Sometimes those orderly atoms create neat side-effects, like piezoelectricity, which is the effect of creating an electrical charge in a crystal by compressing it. Stressing the bonds between the atoms of some crystals causes electrons to build up on one side, creating a charge difference over the body of the crystal. Other crystals do this when you heat or cool them; these are called pyroelectric crystals.

The new cold fusion experiment went something like this: scientists inserted a small pyroelectric crystal (lithium tantalite) inside a chamber filled with hydrogen. Warming the crystal by about 100 degrees produced a huge electrical field of about 100,000 volts across the small crystal.

The tip of a metal wire was inserted near the crystal, which concentrated the charge to a single, powerful point. Remember, hydrogen nuclei have a positive charge, so they feel the force of an electric field, and this one packed quite a wallop! The huge electric field sent the nuclei careening away, smacking into other hydrogen nuclei on their way out. Instead of using intense heat or pressure to get nuclei close enough together to fuse, this new experiment used a very powerful electric field to slam atoms together.

Unlike some previous claims of room-temperature fusion, this one makes intuitive sense: its just another way to get atoms close enough together for the strong force to take over and do the rest. Once the reaction got going, the scientists observed not only the production of helium nuclei, but other tell-tale signs of fusion such as free neutrons and high energy radiation.

This experiment has been repeated successfully and other scientists have reviewed the results: it looks like the real thing this time.

For the time being, don't expect fusion to become a readily available energy option. The current cold fusion apparatus still takes much more energy to start up than you get back out, and it may never end up breaking even. In the mean time, the crystal-fusion device might be used as a compact source of neutrons and X-rays, something that could turn out to be useful making small scanning machines. But it really may not be long until we have the first nuclear fusion-powered devices in common use.

So cold fusion is back, perhaps to stay. After many fits and starts, its finally time for everyday fusion to come in out of the cold.




Posts: 131433
Fusion device

UCLA researchers (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.
They placed a lithium tantalate (LiTaO3) pyroelectric crystal, bathed in deuterium gas, so that one side touches a copper disc. The setup was then cooled to -33ºC and then heated to about 7 ºC for three and a half minutes.


A tiny tungsten probe is then placed at the centre of the copper disc. When the crystal is subsequently heated, a very large electric field is produced at the end of the tungsten tip, about 25 billion volts per metre.
(The crystal is asymmetric and, as a result, heating the material causes positive and negative charges to migrate to opposite ends of the crystal, setting up an electric field. The phenomenon is known as the pyroelectric effect.)
This field gradient is so high (10e7 electron volts) that it strips the electrons from nearby deuterium atoms. The ionised 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 count!
Although the amount of energy produced in this initial experiment was miniscule (~1e-8 joules).
Fusion technology might one day, in theory like the Sun fuses atoms in thermonuclear reactions that create light and heat, lead to a new source of clean energy.
Read more (pdf)

-- Edited by Blobrana at 15:08, 2005-05-19

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