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| Coming in out of the cold: Cold fusion, for real |
| 2005-06-12 |
| A different approach, not yet net energy producing but does appear to be fusion at room temps ... and explainable, too. PASADENA, CALIF. — For the last few years, mentioning cold fusion around scientists (myself included) has been a little like mentioning Bigfoot or UFO sightings. After the 1989 announcement of fusion in a bottle, so to speak, and the subsequent retraction, the whole idea of cold fusion seemed a bit beyond the pale. But that's all about to change. 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 (from -30 F to 45F) 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. If it gets to net positive as an energy source, well ... don't have to tell RB'ers what that will do |
| Posted by:too true |
| #10 Good, I'm glad you're better, phil_b. So far cold fusion uses expensive materials (e.g. Palladium at $183 USD per troy ounce) to produce little or no excess energy or uses lithium tantalite crystals (cost unknown to me) to produce no excess energy. I can do better striking a match. All the facsination with scale-up so "the energy crisis disappears overnight" is wildly-optimistic conjecture with no basis in fact. There are lots of things that don't scale up well. [The billions of dollars that have gone into "hot" fusion research in the last 50 years prove that.] And even if they did scale up well, they may not be cost-effective or they may have large-scale major drawbacks such as the "free neutrons and high energy radiation" mentioned in this article. One of the many problems with "hot" fusion is that everything around it gets a mega-radiation dose and that creates contamination and material properties changes that don't get mentioned in the glossy brochures for non-physicist lab visitors. It's not time to buy Palladium or lithium tantalite crystals yet. |
| Posted by: Tom 2005-06-12 20:32 |
| #9 I was going to leave this alone, but WTF. You start out with Hydrogen atoms and end up with Helium atoms, then fusion has occured. This not open to debate. Only time will tell if this or other mechanisms for cold fusion result in a commercially viable source of energy. And I still don't get the pathological objection to the possibility, which this article demonstrates. It is a precondition to being taken seriously in this field that you deny the possibility of a viable energy source. You will forgive me if it looks to me like a manifestation of the Left/Green/Enviro Western Capitalism is evil and therefore the sky must be falling syndrome, cos cold fusion as a viable energy source means the energy crisis dissapears overnight. Thanks, I feel better now. |
| Posted by: phil_b 2005-06-12 18:40 |
| #8 From the American Institute of Physics Bulletin of Physics News: Pyrofusion: A Room-Temperature, Palm-Sized Nuclear Fusion Device A room-temperature, palm-sized nuclear fusion device has been reported by a UCLA collaboration, potentially leading to new kinds of fusion devices and other novel applications such as microthrusters for MEMS spaceships. The key component of the UCLA device is a pyroelectric crystal, a class of materials that includes lithium niobate, an inexpensive solid that is used to filter signals in cell phones. When heated, a pyroelectric crystal polarizes charge, segregating a significant amount of electric charge near a surface, leading to a very large electric field there. In turn, this effect can accelerate electrons to relatively high (keV) energies (see Update 564). The UCLA researchers (Brian Naranjo, Jim Gimzewski, Seth Putterman) take this idea and add a few other elements to it. In a vacuum chamber containing deuterium gas, they place a lithium tantalate (LiTaO3) pyroelectric crystal so that one of its faces touches a copper disc which itself is surmounted by a tungsten probe. They cool and then heat the crystal, which creates an electric potential energy of about 120 kilovolts at its surface. The electric field at the end of the tungsten probe tip is so high (25 V/nm) that it strips electrons from nearby deuterium atoms. Repelled by the positively charged tip, and crystal field, the resulting deuterium ions then accelerate towards a solid target of erbium deuteride (ErD2), slamming into it so hard that some of the deuterium ions fuse with deuterium in the target. Each deuterium-deuterium fusion reaction creates a helium-3 nucleus and a 2.45 MeV neutron, the latter being collected as evidence for nuclear fusion. In a typical heating cycle, the researchers measure a peak of about 900 neutrons per second, about 400 times the "background" of naturally occurring neutrons. During a heating cycle, which could last from 5 minutes to 8 hours depending on how fast they heat the crystal, the researchers estimate that they create approximately 10-8 joules of fusion energy. [To provide some perspective, it takes about 1,000 joules to heat an 8-oz (237 ml) cup of coffee one degree Celsius.] By using a larger tungsten tip, cooling the crystal to cryogenic temperatures, and constructing a target containing tritium, the researchers believe they can scale up the observed neutron production 1000 times, to more than 106 neutrons per second. (Naranjo, Gimzewski, Putterman, Nature, 28 April 2005). The experimental setup is strikingly simple: "We can build a tiny self-contained handheld object which when plunged into ice water creates fusion," Putterman says. (More information at http://rodan.physics.ucla.edu/pyrofusion .) And in the team's news release: The researchers say that this method of producing nuclear fusion won't be useful for normal power generation, but it might find applications in the generation of neutron beams for research purposes, and perhaps as a propulsion mechanism for miniature spacecraft |
| Posted by: rkb 2005-06-12 13:12 |
| #7 This isn't a device for producing power. It is a neutron generator similar to the accelerated ion neutron generators that have been produced for years. This one is just a little smaller, more reliable, longer lifed, and somewhat more efficient. This article is pop science crock, in that they are slanting it to make you believe some new way of producing energy was discovered. Lousy science reporting aside, it's still a nifty new method for generating neutrons, which will have many benefits for medical treatment, material analysis, etc. |
| Posted by: DO 2005-06-12 12:58 |
| #6 "...the scientists at UCLA cleverly used the structure of an unusual crystal." Hmmm...so just make sure that Scotty can keep the crystal from overloading in the future. |
| Posted by: Ebbereck Uneregum5631 2005-06-12 12:47 |
| #5 "The current cold fusion apparatus still takes much more energy to start up than you get back out" And why would anyone assume that will change? |
| Posted by: Tom 2005-06-12 12:28 |
| #4 For a bomb you're gonna have to reproduce what the big boys have. Sorry about that neighbor ..... |
| Posted by: too true 2005-06-12 11:59 |
| #3 So when do they start selling fusion kits at Wal-Mart and what website will give me hacking tools to turn it into a bomb? I can hardly wait. My neighbor's gonna pay for that atrocious purple garage door. |
| Posted by: Zpaz 2005-06-12 11:51 |
| #2 Does Islam allows cannibalism? I'm guessing that eating christians, heretic muslins and generic infidels is ok. Joooos, of course, are considered unclean. |
| Posted by: SteveS 2005-06-12 11:17 |
| #1 If it gets to net positive as an energy source, well ... don't have to tell RB'ers what that will do Does Islam allows cannibalism (of other Moslems, that is)? |
| Posted by: gromgoru 2005-06-12 11:07 |