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Encyclopedia > List of fusion experiments

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. The Sun is a natural fusion reactor. ... A Plasma lamp In physics and chemistry, a plasma is an ionized gas, and is usually considered to be a distinct phase of matter. ...


The major division is between magnetic confinement and inertial confinement. In magnetic confinement, the tendency of the hot plasma to expand is counteracted by the Lorenz force between currents in the plasma and magnetic fields produced by external coils. The particle densities tend to be in the range of 1018 to 1022 m-3 and the linear dimensions in the range of 0.1 to 10 m. The particle and energy confinement times may range from under a millisecond to over a second, but the configuartion itself is often maintained through input of particles, energy, and current for times that are hundreds or thousands of times longer. Some concepts are capable of maintaining a plasma indefinitely. The magnetic fusion energy (MFE) program seeks to establish the conditions to sustain a nuclear fusion reaction in a plasma that is contained by magnetic fields. ... 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. ... In physics, the Lorentz force is the force exerted on a charged particle in an electromagnetic field. ...


In contrast, with inertial confinement, there is nothing to counteract the expansion of the plasma. The confinement time is simply the time it takes the plasma pressure to overcome the inertia of the particles, hence the name. The densities tend to be in the range of 1031 to 1033 m-3 and the plasma radius in the range of 1 to 100 micrometers. These conditions are obtained by irradiating a millimeter-sized solid pellet with a nanosecond laser or ion pulse. The outer layer of the pellet is ablated, providing a reaction force that compresses the central 10% of the fuel by a factor of 10 or 20 to 103 or 104 times solid density. These microplasmas disperse in a time measured in nanoseconds. For a reactor, a repetition rate of several per second will be needed. Inertia is the tendency of any state of affairs to persist in the absence of external influences. ...

Contents


Magnetic confinement

Within the category of magnetic confinement, there is a basic division between toroidal and open magnetic field topologies. Generally speaking, it is easier to contain a plasma in the direction perpendicular to the field than parallel to it. Parallel confinement can be solved either by bending the field lines back on themselves into circles or, more commonly, toroidal surfaces, or by constricting the bundle of field lines at both ends, which causes some of the particles to be reflected by the mirror effect. The toroidal geometries can be further subdivided according to whether the machine itself has a toroidal geometry, i.e., a solid core through the center of the plasma. The alternative is to dispense with a solid core and rely on currents in the plasma to produce the toroidal field. The magnetic fusion energy (MFE) program seeks to establish the conditions to sustain a nuclear fusion reaction in a plasma that is contained by magnetic fields. ... Topology (Greek topos, place and logos, study) is a branch of mathematics concerned with the study of topological spaces. ... // Geometry In geometry, a torus (pl. ... A magnetic mirror is a plasma confinement device which uses a cylindrical plasma with strong magnetic coils at the ends. ...


Mirror machines have advantages in a simpler geometry and a better potential for direct conversion of particle energy to electricity. They generally require higher magnetic fields than toroidal machines, but the biggest problem has turned out to be confinement. For good confinement there must be more particles moving perpendicular to the field than there are moving parallel to the field. Such a non-Maxwellian velocity distribution is. however, very difficult — and energetically costly — to maintain.


The mirrors' advantage of simple machine geometry is maintained in machine producing compact toroids. There are potential disadvantages for stability by not having a contral conductor, and there is generally less possibility to control and therefore optimize the magnetic geometry. Compact toroid concepts are generally less well developed than those of toroidal machines, which doesn't mean they cannot work better than mainline concepts, but the uncertainty involved is in any case much greater.


Somewhat in a class by itself is the Z-pinch, which has circular field lines. This was one of the first concepts tried but did not prove very successful. Furthermore, there was never a convincing concept for turning the pulsed machine requiring eletrodes into a practical reactor.


The dense plasma focus is a controversial and "non-mainstream" device that relies on currents in the plasma to produce a toroid. It is a pulsed device that depends on a plasma that is not in equilibrium and has the potential for direct conversion of particle energy to electricity. Experiments are ongoing to test relatively new theories to determine if the device has a future.


Toroidal machine

Toroidal machines can be axially symmetric, like the tokamak and the RFP, or unsymmetric, like the stellarator. The additional degree of freedom gained by giving up toroidal symmetry might ultimately be useable to produce better confinement, but the cost is complexity in the engineering, the theory, and the experimental diagnostics. Stellarators typically have a periodicity, e.g. a five-fold rotational symmetry. The RFP, despite some theoretical advantages such as a low magnetic field at the coils, has not proven very successful.


Tokamak

A split image showing the inside of the Joint European Torus shutdown, and running on the right.
A split image showing the inside of the Joint European Torus shutdown, and running on the right.
  • Alcator C-Mod (MIT), US
  • DIII-D (General Atomics), US
  • TFTR, US
  • Japan Torus JT-60 (JAERI)
  • Joint European Torus (JET), UK
  • MAST, UK
  • National Spherical Torus Experiment (NSTX, Princeton Plasma Physics Laboratory), US
  • PEGASUS Toroidal Experiment (University of Wisconsin-Madison), US
  • ITER, FR

A split image of the largest tokamak in the world, the JET, showing hot plasma in the right image during a shot. ... Image File history File links Download high resolution version (1000x579, 150 KB)An image of the inside of the JET tokamak with image on right showing plasma during a shot. ... Image File history File links Download high resolution version (1000x579, 150 KB)An image of the inside of the JET tokamak with image on right showing plasma during a shot. ... Split image of JET with right side showing hot plasma during a shot. ... The Tokomac Fusion Test Reactor (TFTR) was an experimental fusion test reactor built at Princeton Plasma Physics Laboratory (in Princeton, New Jersey) circa 1980. ... JT-60 (JT stands for Japan Torus) is the flagship of Japans magnetic fusion program, run by the Japan Atomic Energy Research Institute (JAERI), Naka Fusion Research Establishment, in Ibaraki Prefecture, Japan. ... Split image of JET with right side showing hot plasma during a shot. ... Cutaway of the ITER Tokamak Torus incasing. ...

Stellarator

A stellarator is a device used to confine a hot plasma with magnetic fields in order to sustain a controlled nuclear fusion reaction. ... Garching is the name of several places in Bavaria, Germany: Garching bei München, in Munich district Garching an der Alz, in Altötting district This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Greifswald (German Greif=griffin, Wald=forest) is a city in Mecklenburg-Western Pomerania, Germany. ... Categories: Stub | Nuclear technology ...

Reversed-Field Pinch (RFP)

Reversed-Field Pinch (RFP) is a toroidal magnetic confinement scheme. ...

Compact Toroid (CT)

Spheromak

Field-Reversed Configuration (FRC)

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. ...

Z-Pinch

The Z machine at Sandia National Laboratories in Albuquerque, New Mexico. ... The Z machine at Sandia National Laboratory. ... Sandia National Laboratories is a major United States Department of Energy research and development national laboratory with two locations, one in Albuquerque, New Mexico and the other in Livermore, California. ...

Inertial confinement

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. ...

Laser driven

  • National Ignition Facility (NIF), US (currently under construciton)
  • The Laboratory for Laser Energetics' Omega Laser
  • The Gekko XII laser at the Institute for Laser Engineering in Osaka, Japan
  • ISKRA-4 and ISKRA-5 Lasers at the Russian Federal Nuclear Center VNIIEF [3]
  • Commissariat à l'Énergie Atomique's Laser Megajoule at Barp, Gironde (Bordeaux, France) [4] (currently under construction)
  • The Naval Research Laboratories' NIKE laser. (Krypton Fluoride gas laser)
  • Asterix IV laser at the Academy of Sciences of the Czech Republic. [5](1 kJ max. output iodine laser at 1.315 micrometre fundamental wavelength)
  • Nova laser (dismantled) at the Lawrence Livermore National Laboratory. (First shot taken, December 1984 - final shot taken and dismantled in 1999)
  • Antares laser (dismantled) at Los Alamos National Laboratory. (40 kJ CO2 laser, largest ever built, production of hot electrons in target plasma due to long wavelength of laser resulted in poor laser/plasma energy coupling)

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 Commissariat à lÉnergie Atomique or CEA, the Atomic Energy Commisson, in English, is a French public establishment of an industrial and commercial character whose mission is to develop all applications of atomic energy, both civilian and military. ... The US Naval Research Laboratory (NRL) is the corporate research laboratory for the United States Navy and the United States Marine Corps and conducts a broad program of scientific research and advanced development. ... Aerial view of the lab and surrounding area. ... Los Alamos National Laboratory, aerial view from 1995. ...

Electrostatic confinement

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. ...

See also

Fusion power The Sun is a natural fusion reactor. ...


  Results from FactBites:
 
List of fusion experiments - Wikipedia, the free encyclopedia (1161 words)
The Nova laser, used for inertial confinement fusion experiments from 1984 until its decomission in 1999.
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.
Experiments are ongoing to test relatively new theories to determine if the device has a future.
  More results at FactBites »

 
 

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