Nuclear Fusion
If two light nuclei are combined to make a heavier nucleus, that is fusion. For all atoms produced lighter than iron, large amounts of energy is given off. The sun and all other stars are powered by nuclear fusion. The first and most common reaction is a star's life cycle is Hydrogen isotopes producing Helium. In man made fusion, the easiest reaction is: Deuterium + Tritium ---> Helium The deuterium is separated from water. Tritium is made by firing neutrons at Lithium to produce Tritium + Helium. Tritium has a half life of 12 years so doesn't occur in nature. This reaction has only been briefly achieved. The neutron flux is very high and irradiates the equipment so that it needs to be remotely handled and disposed of as nuclear waste. It is not as long lived as fission waste. What is never mentioned is whether we have enough lithium. It would be destroyed, transmuted. Would there be enough for batteries? It is a long way from commercial reality. Wikipedia: Fusion power |
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There are various approaches to produce fusion:None are producing commercial power |
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TokamakTokamaks were originally discovered in Soviet Union but have been adopted by researchers around the globe. The gas is heated until its electrons are removed and becomes an electriclly charged plasma. Magnetic fields produced by the coils surrounding the plasma can squeeze the confining the hot plasma away from surrounding material walls. The plasma is heated to a few hundred million degrees Kelvin. At his temperature the particles are moving fast enough to collide with enough force to fuse together.
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HelionHelion claims they are making a fusion engine 1,000 times smaller, over 500 times cheaper, and 10 times faster than other projects. Helion Energy co-founder John Slough in the Redmond, Wash., skunkworks. Slough says his reactor's simplicity and low cost give him a huge advantage in the fusion power race. Photio: John Keatley Source: Popular Mechanics |
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The Fusion Engine provides energy in two ways. Like in a fission reactor, the energy of the scattered neutrons gives off heat that ultimately drives a turbine. Helion is also developing a technique that directly converts energy to electricity. The direct conversion will provide about 70 percent of the outgoing electricity. More: The Weinberg Foundation |
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General Fusion
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Muon catalysed fusion |
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First observed in the 1950s, muon catalysed fusion is a well known scientific process where a subatomic particle known as a muon* captures two hydrogen atoms and forces them to fuse, resulting in energetic particle release and helium.
Scientists have been producing nuclear fusion reactions from muon catalysed fusion for decades – just not consistently or in sufficient volumes for it to be considered a viable energy source. Star Scientific is working towards overcoming these hurdles by perfecting a world-first technique to economically and constantly produce pions, which immediately decay into muons – an innovation that would finally make sustained, controlled muon catalysed fusion a reality. Ref: Wikipedia |
*Muons are the decayed products of a particle called a pion, and are the catalysts in the fusion of two hydrogen isotopes, a process which releases copious amounts of energy. The beauty of the muon is that it acts very much like an electron whose job it is to bond atoms together into molecules. Since a muon is 207 times heavier than an electron, it bumps the electron out of the way and replaces it.
Because the orbit of the heavier muon is much closer, it causes the atoms in the molecule to draw closer until the natural repelling force is overcome and a strong nuclear force brings the atoms together – causing them to fuse. This process kicks the muon out to do its job all over again some 300 times. This fusion gives us energetic neutrons, which are easily converted to heat in a pressurised water reactor – resulting in steam which can be harnessed to create electricity. |
Lockheed MartinTheir team has completed much of the theoretical work over the last four years, and have begun the first experiments. They claim they can heat and ignite the plasma with under a kilowatt of power. The plan is to make a nuclear fusion plant to fit on a truck. They estimate it will be ready by 2024. |
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Aneutronic fusionAneutronic fusion is any form of fusion power where neutrons carry no more than 1% of the total released energy.[1] The most-studied fusion reactions release up to 80% of their energy in neutrons. Successful aneutronic fusion would greatly reduce problems associated with neutron radiation such as ionizing damage, neutron activation, and requirements for biological shielding, remote handling, and safety. Some proponents also see a potential for dramatic cost reductions by converting energy directly to electricity. However, the conditions required to harness aneutronic fusion are much more extreme than those required for the conventional deuterium–tritium (DT) fuel cycle. Various organisations are working on this. |
Candidate aneutronic reactionsThere are a few fusion reactions that have no neutrons as products on any of their branches. Those with the largest cross sections are these: 2D + 3He → 4He + 1p + 18.3 MeV The idea is to have the particles collided and fuse. E.g. Crossfire
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Cold fusion or Low Energy Nuclear Reaction LENR
The cold fusion effect has had a rocky ride. the first claim was seen as a fake, but now is being researched by respectable groups. (I cannot yet tell if it is real or fake - John Davis) An Italian researcher Rossi has claimed success in combining Ni with H. Then using very high terahertz radiation they transmute to copper. NASA researchers are quoted as combining C + H to become N. The current wave of interest was sparked by Italian inventor Andrea Rossi, who showed off his Energy Catalyser or E-Cat in 2011. Rossi claimed that his reactor produced hundreds of kilowatts, and after the demonstration, he went into partnership with an undisclosed US industrial partner. A confidentiality agreement apparently prevents him from giving any details of his work. Other researchers combine Palladium with deuterium with electricity. The electricity forces the deuterium into the palladium. The theory is that there is a nuclear fusion reaction, at a slow rate, and without dangerous radiation. Scientists like to call it a nuclear effect rather than cold fusion. At least 20 labs working independently have published reports of excess heat - heat up to 25 times greater than the electricity going in. One of the main problems is that sometimes it works, and sometimes it doesn't. Some scientists believe it works, other believe it doesn't. |
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Summary of nuclear energy - http://www.energy-without-carbon.org/NuclearSummary Radio active decay - http://www.energy-without-carbon.org/RadioActiveDecay Nuclear Fission - http://www.energy-without-carbon.org/NuclearFission
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