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Encyclopedia > Magnetohydrodynamics

Magnetohydrodynamics (MHD) (magnetofluiddynamics or hydromagnetics) is the academic discipline which studies the dynamics of electrically conducting fluids. Examples of such fluids include plasmas, liquid metals, and salt water. The word magnetohydrodynamics (MHD) is derived from magneto- meaning magnetic field, and hydro- meaning liquid, and -dynamics meaning movement. The field of MHD was initiated by Hannes Alfvén[1], for which he received the Nobel Prize in Physics in 1970. This is a list of academic disciplines (and academic fields). ... In physics, dynamics is the branch of classical mechanics that is concerned with the effects of forces on the motion of objects. ... Electrical conduction is the movement of electrically charged particles through a transmission medium (electrical conductor). ... A fluid is defined as a substance that continually deforms (flows) under an applied shear stress regardless of the magnitude of the applied stress. ... A plasma lamp, illustrating some of the more complex phenomena of a plasma, including filamentation. ... Brine is water saturated or nearly saturated with salt. ... For other senses of this term, see magnetic field (disambiguation). ... A liquid will usually assume the shape of its container A liquid is one of the main states of matter. ... In physics, dynamics is the branch of classical mechanics that is concerned with the effects of forces on the motion of objects. ... Hannes Alfvén (1908-1995), winning the Nobel Prize for his work on magnetohydrodynamics [1]. Hannes Olof Gösta Alfvén (May 30, 1908; Norrköping, Sweden – April 2, 1995; Djursholm, Sweden) was a Swedish plasma physicist who won the 1970 Nobel Prize in Physics for his work developing the... The Nobel Prizes (Swedish: ) are awards in Physics, Chemistry, Literature, Peace, Physiology or Medicine and Economics. ... 1970 (MCMLXX) was a common year starting on Thursday. ...


The idea of MHD is that magnetic fields can induce currents in a moving conductive fluid, which create forces on the fluid, and also change the magnetic field itself. The set of equations which describe MHD are a combination of the Navier-Stokes equations of fluid dynamics and Maxwell's equations of electromagnetism. These differential equations have to be solved simultaneously, either analytically or numerically. Because MHD is a fluid theory, it cannot treat kinetic phenomena, i.e., those in which the existence of discrete particles, or of a non-thermal distribution of their velocities, is important. Electromagnetic induction is the production of an electrical potential difference (or voltage) across a conductor situated in a changing magnetic flux. ... The Navier-Stokes equations, named after Claude-Louis Navier and George Gabriel Stokes, are a set of equations which describe the motion of fluid substances such as liquids and gases. ... Fluid dynamics is the sub-discipline of fluid mechanics dealing with fluids (liquids and gases) in motion. ... In electromagnetism, Maxwells equations are a set of equations developed in the latter half of the nineteenth century by James Clerk Maxwell. ... Electromagnetism is the physics of the electromagnetic field; a field encompassing all of space which exerts a force on particles that possess the property of electric charge, and is in turn affected by the presence and motion of those particles. ... A simulation of airflow into a duct using the Navier-Stokes equations A differential equation is a mathematical equation for an unknown function of one or several variables which relates the values of the function itself and of its derivatives of various orders. ... In mathematics, simultaneous equations are a set of equations where variables are shared. ... Numerical analysis is the study of approximate methods for the problems of continuous mathematics (as distinguished from discrete mathematics). ... Kinetic energy (also called vis viva, or living force) is energy possessed by a body by virtue of its motion. ...

Contents

Ideal and Resistive MHD

MHD Simulation of the Solar Wind
MHD Simulation of the Solar Wind

The simplest form of MHD, Ideal MHD, assumes that the fluid has so little resistivity that it can be treated as a perfect conductor. In ideal MHD, Lenz's law dictates that the fluid is in a sense tied to the magnetic field lines. To be more precise, in ideal MHD, a small rope-like volume of fluid surrounding a field line will continue to lie along a magnetic field line, even as it is twisted and distorted by fluid flows in the system. The connection between magnetic field lines and fluid in ideal MHD fixes the topology of the magnetic field in the fluid -- for example, if a set of magnetic field lines are tied into a knot, then they will remain so as long as the fluid/plasma has negligible resistivity. This difficulty in reconnecting magnetic field lines makes it possible to store energy by moving the fluid or the source of the magnetic field. The energy can then become available if the conditions for ideal MHD break down, allowing magnetic reconnection that releases the stored energy from the magnetic field. Solar wind simulation on a Cray T3E. For the Magnetohydrodynamics article. ... Electrical resistivity (also known as specific electrical resistance) is a measure of how strongly a material opposes the flow of electric current. ... A perfect conductor is an electrical conductor with no resistivity. ... Lenzs law (pronounced (IPA) ) was formulated by German physicist Heinrich Lenz in 1833 and gives the direction of the induced electromotive force (emf) resulting from electromagnetic induction. ... A Möbius strip, an object with only one surface and one edge; such shapes are an object of study in topology. ... Magnetic reconnection is the process whereby magnetic field lines from different magnetic domains are spliced to one another, changing the overall topology of a magnetic field. ...


Ideal MHD Equations

The ideal MHD equations consist of the continuity equation (mass), the momentum equation, Ampere's Law in the limit of no electric field and no electron diffusivity, and a temperature evolution equation. As with any fluid description to a kinetic system, a closure approximation must be applied to highest moment of the particle distribution equation. This is often accomplished with approximations to the heat flux through a condition of adiabaticity or isothermality. All the examples of continuity equations below express the same idea; they are all really examples of the same concept. ... In classical mechanics, momentum (pl. ... In physics, Ampères law is the magnetic equivalent of Gausss law, discovered by André-Marie Ampère. ... Conservation of energy states that the total amount of energy in an isolated system remains constant, although it may change forms (for instance, friction turns kinetic energy into thermal energy). ...


Applicability of Ideal MHD to plasmas

Ideal MHD is only strictly applicable when:

  1. The plasma is strongly collisional, so that the time scale of collisions is shorter than the other characteristic times in the system, and the particle distributions are therefore close to Maxwellian.
  2. The resistivity due to these collisions is small. In particular, the typical magnetic diffusion times over any scale length present in the system must be longer than any time scale of interest.
  3. We are interested in length scales much longer than the ion skin depth and Larmor radius perpendicular to the field, long enough along the field to ignore Landau damping, and time scales much longer than the ion gyration time (system is smooth and slowly evolving).

The importance of resistivity

In an imperfectly conducting fluid, the magnetic field can generally move through the fluid, following a diffusion law with the resistivity of the plasma serving as a diffusion constant. This means that solutions to the ideal MHD equations are only applicable for a limited time for a region of a given size before diffusion becomes too important to ignore. One can estimate the diffusion time across a Solar active region (from collisional resistivity) to be hundreds to thousands of years, much longer than the actual lifetime of a sunspot -- so it would seem reasonable to ignore the resistivity. By contrast, a meter-sized volume of seawater has a magnetic diffusion time measured in milliseconds. Ficks laws of diffusion describe diffusion, and define the diffusion coefficient D. // History Ficks laws of diffusion were derived by Adolf Fick in the year 1855. ...


Even in physical systems which are large and conductive enough that simple estimates suggest that we can ignore the resistivity, resistivity may still be important: many instabilities exist that can increase the effective resistivity of the plasma by factors of more than a billion. The enhanced resistivity is usually the result of the formation of small scale structure like current sheets or fine scale magnetic turbulence, introducing small spatial scales into the system over which ideal MHD is broken and magnetic diffusion can occur quickly. When this happens, Magnetic Reconnection may occur in the plasma to release stored magnetic energy as waves, bulk mechanical acceleration of material, particle acceleration, and heat. Magnetic reconnection in highly conductive systems is important because it concentrates energy in time and space, so that gentle forces applied to a plasma for long periods of time can cause violent explosions and bursts of radiation. Instability in systems is generally characterized by some of the outputs or internal states growing without bounds. ... Magnetic reconnection is the process whereby magnetic field lines from different magnetic domains are spliced to one another, changing the overall topology of a magnetic field. ... This article is about waves in the most general scientific sense. ... Acceleration is the time rate of change of velocity, and at any point on a velocity-time graph, it is given by the slope of the tangent to that point In physics or physical science, acceleration (symbol: a) is defined as the rate of change (or derivative with respect to... In a compressible sound transmission medium - mainly air - air particles get an accelerated motion: the particle acceleration or sound acceleration with the symbol a in metre/second². In acoustics or physics, acceleration (symbol: a) is defined as the rate of change (or time derivative) of velocity. ... In physics, heat, symbolized by Q, is defined as transfer of thermal energy [1] Generally, heat is a form of energy transfer associated with the different motions of atoms, molecules and other particles that comprise matter when it is hot and when it is cold. ...


When the fluid cannot be considered as completely conductive, but the other conditions for ideal MHD are satisfied, it is possible to use an extended model called resistive MHD. This includes an extra term in Ampere's Law which models the collisional resistivity. Generally MHD computer simulations are at least somewhat resistive because their computational grid introduces a numerical resistivity. In physics, Ampères law is the magnetic equivalent of Gausss law, discovered by André-Marie Ampère. ...


The importance of kinetic effects.

Another limitation of MHD (and fluid theories in general) is that they depend on the assumption that the plasma is strongly collisional (this is the first criterion listed above), so that the time scale of collisions is shorter than the other characteristic times in the system, and the particle distributions are Maxwellian. This is usually not the case in fusion, space and astrophysical plasmas. When this is not the case, or we are interested in smaller spatial scales, it may be necessary to use a kinetic model which properly accounts for the non-Maxwellian shape of the distribution function. However, because MHD is very simple, and captures many of the important properties of plasma dynamics, it is often qualitatively accurate, and is almost invariably the first model tried. The Maxwell-Boltzmann distribution is a probability distribution with applications in physics and chemistry. ...


Effects which are essentially kinetic and not captured by fluid models include double layers, a wide range of instabilities, chemical separation in space plasmas and electron runaway. Saturnian aurora whose reddish colour is characteristic of ionized hydrogen plasma. ...


Structures in MHD systems

Schematic view of the different current systems which shape the Earth's magnetosphere
Schematic view of the different current systems which shape the Earth's magnetosphere

In many MHD systems, most of the electric current is compressed into thin, nearly-two-dimensional ribbons termed current sheets. These can divide the fluid into magnetic domains, inside of which the currents are relatively weak. Current sheets in the solar corona are thought to be between a few meters and a few kilometers in thickness, which is quite thin compared to the magnetic domains (which are thousands to hundreds of thousands of kilometers across). Another example is in the earth's magnetosphere, where current sheets separate topologically distinct domains, isolating most of the earth's ionosphere from the solar wind. Image File history File links Download high resolution version (984x765, 81 KB) Summary Schematic of the currents in the Earths magnetosphere, from The art of mapping the Earths magnetosphere by David P. Stern Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version... Image File history File links Download high resolution version (984x765, 81 KB) Summary Schematic of the currents in the Earths magnetosphere, from The art of mapping the Earths magnetosphere by David P. Stern Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version... A current sheet is an electrical current that is confined to a surface, rather than being spread through a volume of space. ... A magnetosphere is the region around an astronomical object in which phenomena are dominated or organized by its magnetic field. ... Relationship of the atmosphere and ionosphere The ionosphere is the part of the atmosphere that is ionized by solar radiation. ... The plasma in the solar wind meeting the heliopause For the British comic, see Solar Wind (comic). ...


Extensions to magnetohydrodynamics

Resistive MHD

Resistive MHD describes magnetized fluids with non-zero electron diffusivity. This diffusivity leads to a breaking in the magnetic topology.


Extended MHD

Extended MHD describes a class of phenomena in plasmas that are higher order than resistive MHD, but which can adequately be treated with a single fluid description. These include the effects of Hall physics, electron pressure gradients, finite Larmor Radii in the particle gyromotion, and electron inertia.


Two-Fluid MHD

Two-Fluid MHD describes plasmas that include a non-negligible electric field. As a result, the electron and ion momenta must be treated separately. This description is more closely tied to Maxwell's equations as an evolution equation for the electric field exists.


Hall MHD

In 1960, M. J. Lighthill criticized the applicability of ideal or resistive MHD theory for plasmas [2]. It concerned the neglect of the "Hall current term", a frequent simplification made in magnetic fusion theory. Hall-magnetohydrodynamics (HMHD) takes into account this electric field description of magnetohydrodynamics [3]


Applications

Geophysics

The fluid core of the Earth and other planets is theorized to be a huge MHD dynamo that generates the Earth's magnetic field due to the motion of the molten rock. Such dynamos work by stretching magnetic field lines that thread through turbulent or sheared flows in a conductive fluid: the total length of magnetic field line in a particular volume determines the strength of the magnetic field, so stretching the field lines increases the magnetic field. Adjectives: Terrestrial, Terran, Telluric, Tellurian, Earthly Atmosphere Surface pressure: 101. ... The Dynamo theory proposes a mechanism by which a celestial body such as the Earth generates a magnetic field. ... Dynamo, or Dinamo, may refer to: Dynamo, an electrical generator Dynamo (sports society) of the Soviet Union Operation Dynamo, the 1940 mass evacuation at Dunkirk Dynamo, the rock band based in Belfast Dynamo theory, a theory relating to magnetic fields of celestial bodies Dynamo Open Air, annual heavy metal music... The magnetosphere shields the surface of the Earth from the charged particles of the solar wind. ...


Astrophysics

MHD applies quite well to astrophysics since over 99% of baryonic matter content of the Universe is made up of plasma, including stars, the interplanetary medium (space between the planets), the interstellar medium (space between the stars), nebulae and jets. Many astrophysical systems are not in local thermal equilibrium, and therefore require an additional kinematic treatment to describe all the phenomena within the system (see Astrophysical plasma). In particle physics, the baryons are a family of subatomic particles including the proton and the neutron (collectively called Greek barys, meaning heavy, as they are heavier than the other main groups of particles. ... For alternate meanings see star (disambiguation) Hundreds of stars are visible in this image taken by the Hubble Space Telescope of the Sagittarius Star Cloud in the Milky Way Galaxy. ... Heliospheric current sheet, the largest structure in the Solar System, results from the influence of the Suns rotating magnetic field on the plasma in the interplanetary medium (Solar Wind) [1]. (click to enlarge) The interplanetary medium is the material which fills the solar system and through which all the... The interstellar medium (or ISM) is the name astronomers give to the tenuous gas and dust that pervade interstellar space. ... The Triangulum Emission Nebula NGC 604 lies in a spiral arm of Galaxy M33, 2. ... Relativistic Jet. ... Heliospheric current sheet, the largest structure in the Solar System, resulting from the influence of the Suns rotating magnetic field on the plasma in the interplanetary medium (Solar Wind) [1]. The wavy spiral shape has been likened to a ballerinas skirt, and carries a tiny 10-10 amps...


Sunspots are caused by the Sun's magnetic fields, as Joseph Larmor theorized in 1919. The solar wind is also governed by MHD. The differential solar rotation may be the long term effect of magnetic drag at the poles of the Sun, an MHD phenomenon due to the Parker spiral shape assumed by the extended magnetic field of the Sun. A sunspot is a region on the Suns surface (photosphere) that is marked by a lower temperature than its surroundings and intense magnetic activity, which inhibits convection, forming areas of low surface temperature. ... The Sun is the star at the center of the Solar System. ... Sir Joseph Larmor (July 11, 1857 - May 19, 1942), an Irish physicist, mathematician and politician, researched electricity, dynamics, and thermodynamics. ... Year 1919 (MCMXIX) was a common year starting on Wednesday (link will display the full calendar). ... The plasma in the solar wind meeting the heliopause For the British comic, see Solar Wind (comic). ... Since the sun is composed of a gaseous plasma, it does not have a fixed rotation rate. ... Heliospheric current sheet, the largest structure in the Solar System, is the three-dimensional form of the Parker spiral, that results from the influence of the Suns rotating magnetic field on the plasma in the interplanetary medium (Solar Wind) [1]. (click to enlarge) The Parker spiral is the shape...


Previously, theories describing the creation of the Sun and planets could not explain how the Sun has 99.87% of the mass, yet only 0.54% of the angular momentum in the solar system. In a closed system such as the cloud of gas and dust from which the Sun was formed, mass and angular momentum are both conserved. That conservation would imply that as the mass concentrated in the center of the cloud to form the Sun, it would spin up, much like a skater pulling their arms in. The high speed of rotation predicted by early theories would have flung the proto-Sun apart before it could have formed. However, magnetohydrodynamic effects transfer the Sun's angular momentum into the outer solar system, slowing its rotation. The Sun is the star at the center of the Solar System. ... The eight planets and three dwarf planets of the Solar System. ... This gyroscope remains upright while spinning due to its angular momentum. ... Major features of the Solar System (not to scale; from left to right): Pluto, Neptune, Uranus, Saturn, Jupiter, the asteroid belt, the Sun, Mercury, Venus, Earth and its Moon, and Mars. ... In thermodynamics, a closed system, as contrasted with an isolated system, can exchange heat and work, but not matter, with its surroundings. ... This gyroscope remains upright while spinning due to its angular momentum. ... In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves. ...


Breakdown of ideal MHD (in the form of magnetic reconnection) is known to be the cause of solar flares, the largest explosions in the solar system. The magnetic field in a solar active region over a sunspot can become quite stressed over time, storing energy that is released suddenly as a burst of motion, X-rays, and radiation when the main current sheet collapses, reconnecting the field. Magnetic reconnection is the process whereby magnetic field lines from different magnetic domains are spliced to one another, changing the overall topology of a magnetic field. ... A solar flare is a violent explosion in the Suns atmosphere with an energy equivalent to tens of millions of hydrogen bombs. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Radiation as used in physics, is energy in the form of waves or particles. ...


Engineering

MHD is related to engineering problems such as plasma confinement, liquid-metal cooling of nuclear reactors, and electromagnetic casting (among others). Engineering is the design, analysis, and/or construction of works for practical purposes. ... Internal view of the JET tokamak superimposed with an image of a plasma taken with a visible spectrum video camera. ... Core of a small nuclear reactor used for research. ... Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field. ...


In early 1990s, Mitsubishi built a boat, the 'Yamato', which uses a magnetohydrodynamic drive, is driven by a liquid helium-cooled superconductor, and can travel at 15 km/h. Mitsubishi Logo The Mitsubishi Group ), Mitsubishi Group of Companies, or Mitsubishi Companies, all refer to a large grouping of independently operated Japanese companies which share the Mitsubishi brand name. ... The Yamato 1 on display in Kobe, Japan A MHD thruster from the boat, at the Ship Science Museum in Tokyo. ... A Magnetohydrodynamic drive or MHD propulsor, is a method proposed for propelling seagoing vessels. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Standard atomic weight 4. ... Superconductivity is a phenomenon occurring in certain materials at low temperatures, characterised by the complete absence of electrical resistance and the damping of the interior magnetic field (the Meissner effect. ... Kilometre per hour (American spelling: kilometer per hour) is a unit of both speed (scalar) and velocity (vector). ...


MHD power generation fueled by potassium-seeded coal combustion gas showed potential for more efficient energy conversion (the absence of solid moving parts allows operation at higher temperatures), but failed due to cost prohibitive technical difficulties.[4]


Trivia

The ebbing salty water flowing past London's Waterloo Bridge interacts with the Earth's magnetic field to produce a potential difference between the two river-banks. Michael Faraday tried this experiment in 1832 but the current was too small to measure with the equipment at the time,[5] and the river bed contributed to short-circuiting the signal. However, by the same process, Dr. William Hyde Wollaston was able to measure the voltage induced by the tide in the English Channel in 1851.[6] This article is about the bridge in London For other uses, see Waterloo Bridge (disambiguation). ... The magnetosphere shields the surface of the Earth from the charged particles of the solar wind. ... Michael Faraday, FRS (September 22, 1791 – August 25, 1867) was an English chemist and physicist (or natural philosopher, in the terminology of that time) who contributed significantly to the fields of electromagnetism and electrochemistry. ... William Hyde Wollaston William Hyde Wollaston FRS (August 6, 1766 – December 22, 1828) was an English chemist and physicist who is famous for discovering two chemical elements and for developing a way to process platinum ore. ...


History

The first recorded use of the word magnetohydrodynamics is by Hannes Alfvén in 1942: Hannes Alfvén (1908-1995), winning the Nobel Prize for his work on magnetohydrodynamics [1]. Hannes Olof Gösta Alfvén (May 30, 1908; Norrköping, Sweden – April 2, 1995; Djursholm, Sweden) was a Swedish plasma physicist who won the 1970 Nobel Prize in Physics for his work developing the...

"At last some remarks are made about the transfer of momentum from the Sun to the planets, which is fundamental to the theory (§11). The importance of the magnetohydrodynamic waves in this respect is pointed out." [7]

Notes

  1. ^ Alfven, H., "Existence of electromagnetic-hydrodynamic waves" (1942) Nature, Vol. 150, pp. 405
  2. ^ M. J. Lighthill, "Studies on MHD waves and other anisotropic wave motion," Phil. Trans. Roy. Soc., London, vol. 252A, pp. 397-430, 1960.
  3. ^ E.A. Witalis, "Hall Magnetohydrodynamics and Its Applications to Laboratory and Cosmic Plasma", IEEE Transactions on Plasma Science (ISSN 0093-3813), vol. PS-14, Dec. 1986, p. 842-848.
  4. ^ http://navier.stanford.edu/PIG/C4_S9.pdf
  5. ^ Dynamos in Nature by David P. Stern
  6. ^ McKetta J McKetta, "Encyclopedia of Chemical Processing and Design: Volume 66" (1999)
  7. ^ Alfvén, H., "On the cosmogony of the solar system III", Stockholms Observatoriums Annaler, vol. 14, pp.9.1-9.29

See also


MHD in fiction: Electrohydrodynamics (EHD) is the study of the dynamics of electrically conducting fluids. ... An important field of plasma physics is the stability of the plasma. ... Shocks and discontinuities are transition layers where the plasma properties change from one equilibrium state to another. ... Computational Magnetohydrodynamics (CMHD) is a rapidly developing branch of Magnetohydrodynamics that uses numerical methods and algorithms to solve and analyze problems that involve electrically conducting fluids. ... Magnetic reconnection is the process whereby magnetic field lines from different magnetic domains are spliced to one another, changing the overall topology of a magnetic field. ... A cluster of double layers forming in an Alfvén wave, about a sixth of the distance from the left. ... A magnetosonic wave is a transverse wave of ions (and electrons) in a magnetized plasma propagating perpendicular to the stationary magnetic field. ... Ferrofluid on glass, with a magnet underneath. ... // The MHD (magnetohydrodynamic) generator or dynamo transforms thermal energy or kinetic energy directly into electricity. ... Principles of an MHD sensor MHD sensors are used for precision measurements of angular velocities in inertial navigation systems (i. ... A Magnetohydrodynamic drive or MHD propulsor, is a method proposed for propelling seagoing vessels. ... The most common flowmeter, apart from the mechanical flow meters, is the magnetic flow meter. ... Core of a small nuclear reactor used for research. ... Hot metal work from a blacksmith In chemistry, a metal (Greek: Metallon) is an element that readily loses electrons to form positive ions (cations) and has metallic bonds between metal atoms. ...


The Hunt for Red October is Tom Clancys first novel, published in 1984. ... In Tom Clancys novel The Hunt for Red October and the movie based on it, the caterpillar drive is a form of submarine propulsion that is much quieter than conventional propellers. ... This article or section does not cite its references or sources. ... Valhalla Rising is a 2001 Clive Cussler book in the Dirk Pitt series. ... Dark Watch is a brand-new book written by Clive Cussler and it was co-authored with Jack Du Brul. ...

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 Internal view of the JET tokamak superimposed with an image of a plasma taken with a visible spectrum video camera. ... The nucleus of an atom is the very small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons). ... 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. ... neutron flux n : the rate of flow of neutrons; the number of neutrons passing through a unit area in unit time via dictionary. ... 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. ... 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) is a concept for retaining a plasma using an electrostatic field. ... 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. ... Doctor Who novel, see Cold Fusion (Doctor Who). ...

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) | UCLA ET (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. ... ITER is an international tokamak (magnetic confinement fusion) research project designed to demonstrate the scientific and technological feasibility of a full-scale fusion power reactor. ... 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. ... The UCLA Electric Tokamak is a low field (0. ... 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. ... Look up demo in Wiktionary, the free dictionary. ...


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) | Luli2000 (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. ... LULI2000 is a high-power laser system dedicated to scientific research. ... 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. ...

References

  • P. A. Davidson, "An Introduction to Magnetohydrodynamics", May 2001 452 p ISBN 0-521-79487-0
  • Jordan, R.,"A statistical equilibrium model of coherent structures in magnetohydrodynamics". Nonlinearity 8 (July 1995) 585-613.
  • Hurricane, O. A., B. H. Fong, and S. C. Cowley, "Nonlinear magnetohydrodynamic detonation: Part I". Physics of Plasmas Vol 4(10) pp. 3565-3580. October 1997.
  • Tabar, M. R. Rahimi, and S. Rouhani, "Turbulent Two Dimensional Magnetohydrodynamics and Conformal Field Theory". Department of Physics, Sharif University of Technology. Institute for Studies in Theoretical Physics and Mathematics. Tehran, Iran. arXiv:hep-th/9503005 v1 1 Mar 1995.
  • Pai, Shih-I. "Magnetogasdynamics and Plasma Dynamics". Vienna: Springer-Verlag, 1962. 197 p. ISBN 0-387-80608-3
  • Biskamp, Dieter. "Nonlinear Magnetohydrodynamics". Cambridge, England: Cambridge University Press, 1993. 378 p. ISBN 0-521-59918-0
  • Ferraro, Vincenzo Consolato Antonio and Plumpton, Charles. "An Introduction to Magneto-Fluid Mechanics", 2nd ed.
  • Roberts, P.H. "Introduction to Magnetohydrodynamics". London: Longmans Green, 1967.
  • Kulikovskiy, A.G. & Lyubimov, G.A. "1965 Magnetohydrodynamics". Addison&Wesley, Massachusetts.
  • Sutton, G. W., and A. Sherman, "Engineering Magnetohydrodynamics", McGraw-Hill Book Company, New York, 1965.
  • "Magnetohydrodynamic Generators with Nonequilibrium Ionization", AIAA Journal, Vol. 3, April, 1965, p 591.
  • Hughes, W., and F. Young, "The Electromagnetodynamics of Fluids", New York, John Wiley & Sons Inc. 1966.
  • Dr. James B. Calvert, "Magnetohydrodynamics", 2002-10-20
  • David P. Stern, NASA, "The Sun's Magnetic Cycle"
  • Jean-Pierre Petit, CNRS (France), "Magnetohydrodynamics (MHD)"
  • Bansal, J.L. "Magneto Fluid Dynamics of Viscous Fluids". (1994) Jaipur Publishing House, Jaipur, India.

  Results from FactBites:
 
Magnetohydrodynamics - Wikipedia, the free encyclopedia (2135 words)
Magnetohydrodynamics (MHD) (magnetofluiddynamics or hydromagnetics) is the academic discipline which studies the dynamics of electrically conducting fluids.
The word magnetohydrodynamics (MHD) is derived from magneto- meaning magnetic field, and hydro- meaning liquid, and -dynamics meaning movement.
The fluid core of the Earth and other planets is theorized to be a huge MHD dynamo that generates the Earth's magnetic field due to the motion of the molten rock.
magnetohydrodynamics: Definition and Much More from Answers.com (2891 words)
Magnetohydrodynamic (MHD) phenomena occur naturally in the Earth's interior, constituting the dynamo that produces the Earth's magnetic field; in the magnetosphere that surrounds the Earth; and in the Sun and throughout astrophysics.
In the laboratory, magnetohydrodynamics is important in the magnetic confinement of plasmas in experiments on controlled thermonuclear fusion.
Magnetohydrodynamic principles are also used in plasma accelerators for ion thrusters for spacecraft propulsion, for light-ion-beam powered inertial confinement, and for magnetohydrodynamic power generation.
  More results at FactBites »

 
 

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