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Encyclopedia > Fusion gain factor
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The fusion energy gain factor, usually expressed with the symbol Q, is the ratio of fusion power produced in a nuclear fusion reactor to the power required to maintain the plasma in steady state. Image File history File links Wiki_letter_w. ... The Sun is a natural fusion reactor. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... A Plasma lamp In physics and chemistry, a plasma is an ionized gas, and is usually considered to be a distinct phase of matter. ... For alternative meanings see steady state (disambiguation). ...


In a fusion power reactor a plasma must be maintained at a high temperature in order that nuclear fusion can occur. Some of this power comes from the fraction of the fusion power contained in charged products which remain in the plasma. This power may be designated fchPfus. The rest, designated Pheat comes from external sources required for heating, some of which may also serve additional purposes like current drive and profile control. This power is lost through various processes to the walls of the plasma chamber. In most reactor designs, various constraints result in this heat leaving the reactor chamber at a relatively low temperature, so that little or none of it can be recovered as electrical power. In these reactors, electrical power is produced from the fraction of the fusion power contained in neutrons, (1-fch)Pfus. The neutrons are not held back by the magnetic fields (in magnetic confinement fusion) or the dense plasma (in inertial confinement fusion) but are absorbed in a surrounding "blanket". Due to various exothermic and endothermic reactions, the blanket may have a power gain factor a few percent higher or lower than 100%, but that will be neglected here. The neutron power heats a working medium such as helium gas or liquid lithium to a high temperature, and the working medium is used to produce electricity at some efficiency ηelec, so that Pelec = ηelec(1-fch)Pfus. A fraction frecirc of the electrical power is recirculated to run the reactor systems. Power is needed for lighting, pumping, producing magnetic fields, etc., but most is required for plasma heating so we can write Pheat = ηheatPelec, where ηheat is substantially the efficiency with which electrical power is converted to the form of power needed to heat the plasma. Magnetic Fusion Energy (MFE) is a sustained nuclear fusion reaction in a plasma that is contained by magnetic fields. ... Inertial confinement fusion using lasers rapidly progressed in the late 1970s and early 1980s from being able to deliver only a few joules of laser energy (per pulse) to a fusion target to being able to deliver tens of kilojoules to a target. ... Exothermic means to release energy in the form of heat. ... In thermodynamics, the word endothermic describes a process or reaction that absorbs energy in the form of heat. ...


The heating power can thus be related to the fusion power by the following equation:

Pheat = ηheatfrecircηelec(1-fch)Pfus

The fusion energy gain factor is then

Q = Pfus/Pheat = (ηheatfrecircηelec(1-fch))-1

For the D-T reaction, fch = 0.2. Efficiency values depend on design details but may be in the range of ηheat = 0.7 and ηelec = 0.4. The purpose of a fusion reactor is to sell power, not to recirculate it, so a practical reactor must have frecirc = 0.2 approximately. Lower would be better but will be hard to achieve. Using these values we find for a practical reactor Q = 22. Of course, Q = 15 might be enough and Q = 30 might be achievable, but this simple calculation shows the magnitude of fusion energy gain required.


The goal of ignition, a plasma which heats itself by fusion energy without any external input, corresponds to infinite Q. Note that ignition is not a necessary condition for a practical reactor. On the other hand, achieving Q = 20 requires quality of confinement almost as good as that required to achieve ignition, so the Lawson criterion is still a useful figure of merit. The condition of Q = 1 is referred to as breakeven. It is somewhat arbitrary, but it does mean that a significant fraction (20%) of the heating power comes from fusion, so that fusion heating can be studied. Above Q = 5 the fusion heating power is greater than the external heating power. This article or section does not cite its references or sources. ...


The one channel of energy loss that is independent of the confinement scheme and practically impossible to avoid is Bremsstrahlung radiation. Like the fusion power density, the Bremsstrahlung power density depends on the square of the plasma density, but it does not increase as rapidly with temperature. By equating the two power densities, one can determine the lowest temperature for which the fusion power can overcome the Bremsstrahlung power. This ignition temperature is about 4 keV for the D-T reaction and about 35 keV for the D-D reaction. (help· info), (from the German bremsen, to brake and Strahlung, radiation, thus, braking radiation), is electromagnetic radiation produced by the acceleration of a charged particle, such as an electron, when deflected by another charged particle, such as an atomic nucleus. ...



Fusion power
v  d  e
Atomic nucleus | Nuclear fusion | Nuclear power | Nuclear reactor | Timeline of nuclear fusion
Plasma physics | Magnetohydrodynamics | Neutron flux | Fusion energy gain factor | Lawson criterion
Methods of fusing nuclei

Magnetic confinement: Tokamak - Spheromak - Stellarator - Reversed field pinch - Field-Reversed Configuration - Levitated Dipole
Inertial confinement: Laser driven - Z-pinch - Bubble fusion (acoustic confinement) - Fusor (electrostatic confinement)
Other forms of fusion: Muon-catalyzed fusion - Pyroelectric fusion - Migma - Cold fusion(disputed) The Sun is a natural fusion reactor. ... A semi-accurate depiction of the helium atom. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... A nuclear power station. ... Core of a small nuclear reactor used for research. ... Timeline of significant events in the study and use of nuclear fusion: 1929 - Atkinson and Houtermans used the measured masses of light elements and applied Einsteins discovery that E=mc² to predict that large amounts of energy could be released by fusing small nuclei together. ... A Plasma lamp In physics and chemistry, a plasma is an ionized gas, and is usually considered to be a distinct phase of matter. ... Magnetohydrodynamics (MHD) (magnetofluiddynamics or hydromagnetics) is the academic discipline which studies the dynamics of electrically conducting fluids. ... neutron flux n : the rate of flow of neutrons; the number of neutrons passing through a unit area in unit time via dictionary. ... This article or section does not cite its references or sources. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... Magnetic Fusion Energy (MFE) is a sustained nuclear fusion reaction in a plasma that is contained by magnetic fields. ... A split image of the largest tokamak in the world, the JET, showing hot plasma in the right image during a shot. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Stellarator magnetic field and magnets A stellarator is a device used to confine a hot plasma with magnetic fields in order to sustain a controlled nuclear fusion reaction. ... Reversed-Field Pinch is a toroidal magnetic confinement scheme. ... A Field-Reversed Configuration (FRC) is a device developed for magnetic fusion energy research that confines a plasma on closed magnetic field lines without a central penetration. ... A Levitated Dipole is a unique form of fusion reactor technology using a solid superconducting torus, magnetically levitated in the reactor chamber. ... Inertial confinement fusion using lasers rapidly progressed in the late 1970s and early 1980s from being able to deliver only a few joules of laser energy (per pulse) to a fusion target to being able to deliver tens of kilojoules to a target. ... In inertial confinement fusion (ICF), nuclear fusion reactions are initiated by heating and compressing a target – a pellet that most often contains deuterium and tritium – by the use of intense laser or ion beams. ... The Z machine at Sandia National Laboratories in Albuquerque, New Mexico. ... Bubble fusion or sonofusion is the common name for a nuclear fusion reaction hypothesized to occur during sonoluminescence, an extreme form of acoustic cavitation; officially, this reaction is termed acoustic inertial confinement fusion (AICF) since the inertia of the collapsing bubble wall confines the energy causing a rise in temperature. ... U.S. Patent 3,386,883 - fusor — June 4, 1968 The Farnsworth–Hirsch Fusor, or simply fusor, is an apparatus designed by Philo T. Farnsworth to create nuclear fusion. ... Inertial electrostatic confinement (often abbreviated as IEC) of a plasma can be achieved with electrostatic fields which accelerate charged particles (either ions or electrons) directly, in a confined space. ... Muon-catalyzed fusion is a process allowing nuclear fusion to take place at room temperature. ... Pyroelectric fusion is a technique for achieving nuclear fusion by using an electric field generated by pyroelectric crystals to accelerate ions of deuterium (tritium might also be used someday) into a metal hydride target also containing detuerium (or tritium) with sufficient kinetic energy to cause these ions to fuse together. ... Migma was a proposed inertial electrostatic confinement fusion reactor designed by Bogdan Maglich around 1973. ... Charles Bennett examines three cold fusion tests cells at the Oak Ridge National Laboratory, USA Cold fusion cell at the US Navy Space and Naval Warfare Systems Center, San Diego, CA (2005) Cold fusion is a theoretical fusion reaction that occurs near room temperature and pressure using relatively simple devices. ...

List of fusion experiments

Magnetic confinement devices
ITER (International) | JET (European) | JT-60 (Japan) | Large Helical Device (Japan) | KSTAR (Korea) | EAST (China) | T-15 (Russia) | DIII-D (USA) | Tore Supra (France) | ASDEX Upgrade (Germany) | TFTR (USA) | NSTX (USA) | NCSX (USA) | Alcator C-Mod (USA) | LDX (USA) | H-1NF (Australia) | MAST (UK) | START (UK) | Wendelstein 7-X (Germany) | TCV (Switzerland) | DEMO (Commercial) Experiments directed toward developing fusion power are invariably done with dedicated machines which can be classified according to the principles they use to confine the plasma fuel and keep it hot. ... Cutaway of the ITER Tokamak Torus in casing. ... Split image of JET with right side showing hot plasma during a shot. ... JT-60 (JT stands for Japan Torus) is the flagship of Japans magnetic fusion program, run by the Japan Atomic Energy Research Institute (JAERI), and the Naka Fusion Research Establishment in Ibaraki Prefecture, Japan. ... Categories: Stub | Nuclear technology ... The KSTAR, or Korean Superconducting Tokamak Advanced Reactor is a magnetic fusion device being built at the Korea Basic Science Institute in Daejon, South Korea. ... The Experimental Advanced Superconducting Tokamak (EAST, internally called HT-7U) is a project being undertaken to construct an experimental superconducting tokamak magnetic fusion energy reactor in Hefei, the capital city of Anhui Province, in eastern China. ... The T-15 is a Russian nuclear fusion research reactor, based on the (Russian-invented) tokamak design. ... DIII-D or D3-D is the name of a tokamak machine developed in the 1980s by General Atomics in San Diego, USA, as part of the ongoing effort to achieve magnetically confined fusion. ... Tore Supra is a tokamak français en activité après larrêt du TFR (Tokamak de Fontenay-aux-Roses) et de Petula (à Grenoble). ... The ASDEX Upgrade divertor tokamak (Axially Symmetric Divertor EXperiment) went into operation at the Max-Planck-Institut für Plasmaphysik, Garching in 1991. ... The Tokamak Fusion Test Reactor (TFTR) was an experimental fusion test reactor built at Princeton Plasma Physics Laboratory (in Princeton, New Jersey) circa 1980. ... The National Spherical Torus Experiment (NSTX) is an innovative magnetic fusion device that was constructed by the Princeton Plasma Physics Laboratory (PPPL) in collaboration with the Oak Ridge National Laboratory, Columbia University, and the University of Washington at Seattle. ... The National Compact Stellarator Experiment (NCSX) is a plasma confinement experiment being conducted at the Princeton Plasma Physics Laboratory. ... Alcator C-Mod is a tokamak, a magnetically confined nuclear fusion device, at the MIT Plasma Science and Fusion Center. ... The Levitated Dipole Experiment (LDX) is a project devoted to researching a type of nuclear fusion which utilizes a floating superconducting torus to provide an axisymmetric magnetic field which is used to contain plasma. ... The H-1 flexible Heliac is a three field-period helical axis stellarator located in the Research School of Physical Sciences and Engineering at the Australian National University. ... The Mega Ampere Spherical Tokamak, or MAST experiment is a nuclear fusion experiment in operation at Culham since December 1999. ... The Small Tight Aspect Ratio Tokamak, or START was a nuclear fusion experiment that used magnetic confinement to hold plasma. ... Magnetic coils and plasma of the Wendelstin 7-X stellarator Plasma vessel of Wendelstein 7-X Wendelstein 7-X is an experimental stellarator (nuclear fusion reactor) currently being built in Greifswald, Germany by the Max-Planck-Institut für Plasmaphysik (IPP), which will be completed by 2012. ... Tokamak à Configuration Variable (TCV): inner view, with the graphite-claded torus. ... The word demo may refer to one of the following. ...


Inertial confinement devices
Laser driven: NIF (USA) | OMEGA laser (USA) | Nova laser (USA) | Novette laser (USA) | Nike laser (USA) | Shiva laser (USA) | Argus laser (USA) | Cyclops laser (USA) | Janus laser (USA) | Long path laser (USA) | 4 pi laser (USA) | LMJ (France) | GEKKO XII (Japan) | ISKRA lasers (Russia) | Vulcan laser (UK) | Asterix IV laser (Czech Republic) | HiPER laser (European)
Non-laser driven:
Z machine (USA) | PACER (USA)
A construction worker inside NIFs 10 meter target chamber. ... The Laboratory for Laser Energetics (LLE) is a scientific research facility which is part of the University of Rochesters south campus, located in Rochester, New York. ... The Nova laser was a laser built at the Lawrence Livermore National Laboratory in 1984 and which conducted advanced inertial confinement fusion experiments until its dismantling in 1999. ... The Novette target chamber with two laser chains visible in background. ... Final amplifier of the Nike laser where laser beam energy is increased from 150 J to ~5 Kj by passing through a krypton/fluorine/argon gas mixture excited by irradiation with two opposing 670,000 volt electron beams. ... The Shiva laser was an extremely powerful 20 beam infrared neodymium glass (silica glass) laser built at Lawrence Livermore National Laboratory in 1977 for the study of inertial confinement fusion and long-scale-length laser-plasma interactions. ... Argus laser overhead view. ... The single beam Cyclops laser at LLNL around the time of its completion in 1975. ... The Janus laser as it appeared in 1975. ... The Long Path laser was an early high energy infrared laser at the Lawrence Livermore National Laboratory used to study inertial confinement fusion. ... Physicist Frank Rainer (inset), who was involved in laser research and development at LLNL since 1966, holds the target chamber seen at the center of the larger picture. ... Laser Mégajoule (LMJ) is an experimental inertial confinement fusion (ICF) device being built in France by the French nuclear science directorate, CEA. Laser Mégajoule plans to deliver about 1. ... GEKKO XII is a high-power 12-beam neodymium doped glass laser at the Osaka Universitys Institute for Laser Engineering completed in 1983, which is used for high energy density physics and inertial confinement fusion research. ... The ISKRA-4 and ISKRA-5 lasers are lasers which were built by the Russian federation at RFNC-VNIIEF in Arzamas-16() with the ~2Kj output ISKRA-4 laser being completed in 1979 and the ~30Kj output ISKRA-5 laser which was completed in 1989. ... The Vulcan laser is an 8 beam 2. ... The Asterix IV laser in Prague (commonly reffered to by the acronym PALS for Prague Asterix Laser System) is a high power photolytically pumped iodine gas laser which is capable of producing ~300 to 500 picosecond long pulses of light at the fundamental line of 1. ... HiPER is an experimental laser-driven inertial confinement fusion (ICF) device currently undergoing preliminary design for possible construction in the European Union starting around 2010. ... Zork universe Zork games Zork Anthology Zork trilogy Zork I   Zork II   Zork III Beyond Zork   Zork Zero   Planetfall Enchanter trilogy Enchanter   Sorcerer   Spellbreaker Other games Wishbringer   Return to Zork Zork: Nemesis   Zork Grand Inquisitor Zork: The Undiscovered Underground Topics in Zork Encyclopedia Frobozzica Characters   Kings   Creatures Timeline   Magic   Calendar... The PACER project, carried out at Los Alamos National Laboratory in the mid-1970s, explored the possibility of a fusion power system that would involve exploding small hydrogen bombs (fusion bombs)—or, as stated in a later proposal, fission bombs—inside an underground cavity. ...


See also: International Fusion Materials Irradiation Facility The International Fusion Material Irradiation Facility, also known as IFMIF, is an international scientific research program designed to test materials for suitability for use in a fusion reactor. ...


 
 

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