Cold fusion

: This article is about the nuclear reaction. For the computer programming language, see ColdFusion.

Other kinds of fusion

This article focuses on the Fleischmann-Pons effect produced in electrolytic cells. This effect has also been observed with other methods of forming hydrides such as gas loading, electromigration and ion implantion. Other forms of fusion have been studied by scientists. Some are "cold" in the sense that no part of the reaction is actually hot (except for the reaction products), some are "cold" in the sense that the energies required are low and the bulk of the material is at a relatively low temperature, and some are "hot", involving reactions which create macroscopic regions of very high temperature and pressure.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

• Fusion with low-energy reactants.
• Muon-catalyzed fusion is a well-established and reproducible fusion process which occurs at ordinary temperatures. It has been studied in detail by Steven Jones in the early 1980s. Because of the energy required to create muons and the fact that muons have limited lifetimes, it is not currently able to produce net energy, and analyses indicate at present that energy production from the reaction is not possible.
• Fusion with high-energy reactants in relatively cold condensed matter. (Energy losses from the small hot spots to the surrounding cold matter will generally preclude any possibility of net energy production.)
• Pyroelectric fusion was reported in April 2005 by a team at UCLA. The scientists used a pyroelectric crystal heated from −30 to 45 degrees Fahrenheit (from −34 to 7 °C) combined with a tungsten needle to produce an electric field of about 25 gigavolts per meter to ionize and accelerate deuterium nuclei into an erbium deuteride target. Though the energy of the deuterium ions generated by the crystal has not been directly measured, the authors used 100 keV (a temperature of about 10⁹ K) as an estimate in their modeling.http://www.nature.com/nature/journal/v434/n7037/extref/nature03575-s1.pdf At these energy levels, two deuterium nuclei can fuse together to produce a helium-3 nucleus, a 2.45 MeV neutron and bremsstrahlung. This experiment has been repeated successfully, and other scientists have confirmed the results. Although it makes a useful neutron generator, the apparatus is not intended for power generation since it requires far more energy than it produces. http://rodan.physics.ucla.edu/pyrofusion/ http://www.aip.org/pnu/2005/split/729-1.html http://www.christiansciencemonitor.com/2005/0606/p25s01-stss.html http://msnbc.msn.com/id/7654627
• Antimatter-initialized fusion uses small amounts of antimatter to trigger a tiny fusion explosion. This has been studied primarily in the context of making nuclear pulse propulsion feasible. This is not near becoming a practical power source, due to the cost of manufacturing antimatter alone.
• In sonoluminescence, acoustic shock waves create temporary bubbles that collapse shortly after creation, producing very high temperatures and pressures. In 2002, Rusi P. Taleyarkhan reported the possibility that bubble fusion occurs in those collapsing bubbles. As of 2005, experiments to determine whether fusion is occurring give conflicting results. If fusion is occurring, it is because the temperature and pressure are sufficiently high to produce hot fusion.
• Fusion with macroscopic regions of high energy plasma:
• "Standard" "hot" fusion, in which the fuel reaches tremendous temperature and pressure inside a fusion reactor, nuclear weapon, or star.
• The Farnsworth-Hirsch Fusor is a tabletop device in which fusion occurs. This fusion comes from high effective temperatures produced by electrostatic acceleration of ions. The device can be built inexpensively, but it too is unable to produce a net power output. These devices have a valid use however, and are commercially sold as a source of neutrons. The ion energy distribution is generally supposed to be nearly mono-energetic, but Todd Rider showed in his doctoral thesis for Massachusetts Institute of Technology that such non-Maxwellian distributions require too much recirculating power to be practically sustainable.