Experiments directed toward developing
fusion power
Fusion power is a proposed form of power generation that would generate electricity by using heat from nuclear fusion, nuclear fusion reactions. In a fusion process, two lighter atomic nucleus, atomic nuclei combine to form a heavier nucleus, whi ...
are invariably done with dedicated machines which can be classified according to the principles they use to confine the
plasma
Plasma or plasm may refer to:
Science
* Plasma (physics), one of the four fundamental states of matter
* Plasma (mineral), a green translucent silica mineral
* Quark–gluon plasma, a state of matter in quantum chromodynamics
Biology
* Blood pla ...
fuel and keep it hot.
The major division is between
magnetic confinement
Magnetic confinement fusion is an approach to generate thermonuclear fusion power that uses magnetic fields to confine fusion fuel in the form of a plasma. Magnetic confinement is one of two major branches of fusion energy research, along with i ...
and
inertial confinement
Inertial confinement fusion (ICF) is a fusion energy process that initiates nuclear fusion reactions by compressing and heating targets filled with thermonuclear fuel. In modern machines, the targets are small spherical pellets about the size of ...
. In magnetic confinement, the tendency of the hot plasma to expand is counteracted by the
Lorentz force
In physics (specifically in electromagnetism) the Lorentz force (or electromagnetic force) is the combination of electric and magnetic force on a point charge due to electromagnetic fields. A particle of charge moving with a velocity in an elect ...
between currents in the plasma and magnetic fields produced by external coils. The particle densities tend to be in the range of to and the linear dimensions in the range of . The particle and energy confinement times may range from under a millisecond to over a second, but the configuration 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.
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
Inertia is the idea that an object will continue its current motion until some force causes its speed or direction to change. The term is properly understood as shorthand for "the principle of inertia" as described by Newton in his first law ...
of the particles, hence the name. The densities tend to be in the range of to and the plasma radius in the range of 1 to 100 micrometers. These conditions are obtained by
irradiating
Irradiation is the process by which an object is exposed to radiation. The exposure can originate from various sources, including natural sources. Most frequently the term refers to ionizing radiation, and to a level of radiation that will serve ...
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 10
3 or times solid density. These microplasmas disperse in a time measured in nanoseconds. For a fusion power reactor, a repetition rate of several per second will be needed.
Magnetic confinement
Within the field of
magnetic confinement
Magnetic confinement fusion is an approach to generate thermonuclear fusion power that uses magnetic fields to confine fusion fuel in the form of a plasma. Magnetic confinement is one of two major branches of fusion energy research, along with i ...
experiments, there is a basic division between
toroidal and open magnetic field
topologies
In mathematics, topology (from the Greek words , and ) is concerned with the properties of a geometric object that are preserved under continuous deformations, such as stretching, twisting, crumpling, and bending; that is, without closing ho ...
. 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.
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 to maintain and energetically costly.
The mirrors' advantage of simple machine geometry is maintained in machines which produce
compact toroid
Compact toroids are a class of toroidal plasma configurations that are self-stable, and whose configuration does not require magnet coils running through the center of the toroid. They are studied primarily in the field of fusion energy, where t ...
s, but there are potential disadvantages for stability in not having a central conductor and there is generally less possibility to control (and thereby optimize) the magnetic geometry. Compact toroid concepts are generally less well developed than those of toroidal machines. While this does not necessarily mean that they cannot work better than mainstream concepts, the uncertainty involved is much greater.
Somewhat in a class by itself is the
Z-pinch
In fusion power research, the Z-pinch (zeta pinch) is a type of plasma confinement system that uses an electric current in the plasma to generate a magnetic field that compresses it (see pinch). These systems were originally referred to simply ...
, which has circular field lines. This was one of the first concepts tried, but it did not prove very successful. Furthermore, there was never a convincing concept for turning the pulsed machine requiring electrodes into a practical reactor.
The
dense plasma focus
A dense plasma focus (DPF) is a type of plasma generating system originally developed as a fusion power device starting in the early 1960s. The system demonstrated scaling laws that suggested it would not be useful in the commercial power role, and ...
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
A tokamak (; russian: токамáк; otk, 𐱃𐰸𐰢𐰴, Toḳamaḳ) is a device which uses a powerful magnetic field to confine plasma in the shape of a torus. The tokamak is one of several types of magnetic confinement devices being d ...
and the
reversed field pinch
A reversed-field pinch (RFP) is a device used to produce and contain near-thermonuclear Plasma (physics), plasmas. It is a Pinch (magnetic fusion), toroidal pinch which uses a unique magnetic field configuration as a scheme to magnetically con ...
(RFP), or asymmetric, like the
stellarator
A stellarator is a plasma device that relies primarily on external magnets to confine a plasma. Scientists researching magnetic confinement fusion aim to use stellarator devices as a vessel for nuclear fusion reactions. The name refers to the ...
. The additional degree of freedom gained by giving up toroidal symmetry might ultimately be usable 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 fivefold rotational symmetry. The RFP, despite some theoretical advantages such as a low magnetic field at the coils, has not proven very successful.
Tokamak
Stellarator
Magnetic mirror
A magnetic mirror, known as a magnetic trap (магнитный захват) in Russia and briefly as a pyrotron in the US, is a type of magnetic confinement device used in fusion power to trap high temperature plasma using magnetic fields. T ...
* Tabletop/Toytop,
Lawrence Livermore National Laboratory
Lawrence Livermore National Laboratory (LLNL) is a federal research facility in Livermore, California, United States. The lab was originally established as the University of California Radiation Laboratory, Livermore Branch in 1952 in response ...
, Livermore CA.
* DCX/DCX-2,
Oak Ridge National Laboratory
Oak Ridge National Laboratory (ORNL) is a U.S. multiprogram science and technology national laboratory sponsored by the U.S. Department of Energy (DOE) and administered, managed, and operated by UT–Battelle as a federally funded research and ...
* ORGA, Akademgorodok, Russia.
* Baseball I/Baseball II
Lawrence Livermore National Laboratory
Lawrence Livermore National Laboratory (LLNL) is a federal research facility in Livermore, California, United States. The lab was originally established as the University of California Radiation Laboratory, Livermore Branch in 1952 in response ...
, Livermore CA.
* 2X/2XIII/2XIII-B,
Lawrence Livermore National Laboratory
Lawrence Livermore National Laboratory (LLNL) is a federal research facility in Livermore, California, United States. The lab was originally established as the University of California Radiation Laboratory, Livermore Branch in 1952 in response ...
, Livermore CA.
*
TMX, TMX-U Lawrence Livermore National Laboratory
Lawrence Livermore National Laboratory (LLNL) is a federal research facility in Livermore, California, United States. The lab was originally established as the University of California Radiation Laboratory, Livermore Branch in 1952 in response ...
, Livermore CA.
*
MFTF
The Mirror Fusion Test Facility, or MFTF, was an experimental magnetic confinement fusion device built using the tandem magnetic mirror design. It was, by far, the largest, most powerful and most expensive mirror machine ever constructed. Due to ...
Lawrence Livermore National Laboratory
Lawrence Livermore National Laboratory (LLNL) is a federal research facility in Livermore, California, United States. The lab was originally established as the University of California Radiation Laboratory, Livermore Branch in 1952 in response ...
, Livermore CA.
*
Gas Dynamic Trap The Gas Dynamic Trap is a magnetic mirror machine being operated at the Budker Institute of Nuclear Physics in Akademgorodok, Russia.
Technical specifications
Dimensions
The plasma inside the machine fills a cylinder of space, 7 meters long and ...
at
Budker Institute of Nuclear Physics
The Budker Institute of Nuclear Physics (BINP) is one of the major centres of advanced study of nuclear physics in Russia. It is located in the Siberian town Akademgorodok, on Academician Lavrentiev Avenue. The institute was founded by Gers ...
, Akademgorodok, Russia.
Toroidal
Z-pinch
In fusion power research, the Z-pinch (zeta pinch) is a type of plasma confinement system that uses an electric current in the plasma to generate a magnetic field that compresses it (see pinch). These systems were originally referred to simply ...
*
Perhapsatron The Perhapsatron was an early fusion power device based on the pinch concept in the 1950s. Conceived by James (Jim) Tuck while working at Los Alamos National Laboratory (LANL), he whimsically named the device on the chance that it might be able to ...
(1953, USA)
*
ZETA
Zeta (, ; uppercase Ζ, lowercase ζ; grc, ζῆτα, el, ζήτα, label= Demotic Greek, classical or ''zē̂ta''; ''zíta'') is the sixth letter of the Greek alphabet. In the system of Greek numerals, it has a value of 7. It was derived f ...
(Zero Energy Thermonuclear Assembly) (1957, United Kingdom)
Reversed field pinch (RFP)
* ETA-BETA II in Padua, Italy (1979–1989)
*
RFX (Reversed-Field eXperiment), Consorzio RFX, Padova, Italy
*
MST
The Master of Studies or Master in Studies (M.St. or MSt; ) is a postgraduate degree at the University of Oxford, University of Cambridge, University of St Andrews, the Australian National University, University of Dublin and the University of Ne ...
(Madison Symmetric Torus),
University of Wisconsin–Madison
A university () is an educational institution, institution of higher education, higher (or Tertiary education, tertiary) education and research which awards academic degrees in several Discipline (academia), academic disciplines. Universities ty ...
, United States
* T2R,
Royal Institute of Technology
The KTH Royal Institute of Technology ( sv, Kungliga Tekniska högskolan, lit=Royal Institute of Technology), abbreviated KTH, is a public research university in Stockholm, Sweden. KTH conducts research and education in engineering and technolo ...
, Stockholm, Sweden
* TPE-RX,
AIST, Tsukuba, Japan
* KTX (Keda Torus eXperiment) in China (since 2015)
Spheromak
A spheromak is an arrangement of plasma formed into a toroidal shape similar to a smoke ring. The spheromak contains large internal electric currents and their associated magnetic fields arranged so the magnetohydrodynamic forces within the s ...
*
Sustained Spheromak Physics Experiment
Field-reversed configuration
A field-reversed configuration (FRC) is a type of plasma device studied as a means of producing nuclear fusion. It confines a plasma on closed magnetic field lines without a central penetration. In an FRC, the plasma has the form of a self-stabl ...
(FRC)
* C-2
Tri Alpha Energy
TAE Technologies, formerly Tri Alpha Energy, is an American company based in Foothill Ranch, California developing aneutronic fusion power. The company's design relies on an advanced beam-driven field-reversed configuration (FRC), which combin ...
* C-2U
Tri Alpha Energy
TAE Technologies, formerly Tri Alpha Energy, is an American company based in Foothill Ranch, California developing aneutronic fusion power. The company's design relies on an advanced beam-driven field-reversed configuration (FRC), which combin ...
* C-2W
TAE Technologies
TAE Technologies, formerly Tri Alpha Energy, is an American company based in Foothill Ranch, California developing aneutronic fusion power. The company's design relies on an advanced beam-driven field-reversed configuration (FRC), which combin ...
* LSX
University of Washington
The University of Washington (UW, simply Washington, or informally U-Dub) is a public research university in Seattle, Washington.
Founded in 1861, Washington is one of the oldest universities on the West Coast; it was established in Seattle a ...
* IPA University of Washington
* HF University of Washington
* IPA- HF University of Washington
Open field lines
Plasma pinch
A pinch (or: Bennett pinch (after Willard Harrison Bennett), electromagnetic pinch, magnetic pinch, pinch effect, or plasma pinch.) is the compression of an electrically conducting Electrical filament, filament by magnetic forces, or a device tha ...
*
Trisops Trisops was an experimental machine for the study of magnetic confinement of plasmas with the ultimate goal of producing fusion power. The configuration was a variation of a compact toroid, a toroidal ( doughnut-shaped) structure of plasma and ma ...
– 2 facing theta-pinch guns
* FF-2B,
Lawrenceville Plasma Physics
Eric J. Lerner (born May 31, 1947) is an American popular science writer, and independent plasma researcher. He wrote the 1991 book ''The Big Bang Never Happened'', which advocates Hannes Alfvén's plasma cosmology instead of the Big Bang theory. ...
, United States
Levitated dipole
A levitated dipole is a type of nuclear fusion reactor design using a superconducting torus which is magnetically levitated inside the reactor chamber. The name refers to the magnetic dipole that forms within the reaction chamber, similar to Eart ...
*
Levitated Dipole Experiment
The Levitated Dipole Experiment (LDX) was an experiment investigating the generation of fusion power using the concept of a levitated dipole. The device was the first of its kind to test the levitated dipole concept and was funded by the United St ...
(LDX), MIT/
Columbia University
Columbia University (also known as Columbia, and officially as Columbia University in the City of New York) is a private research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhatt ...
, United States
Inertial confinement
Laser-driven
Z-pinch
*
Z Pulsed Power Facility
The Z Pulsed Power Facility, informally known as the Z machine or Z, is the largest high frequency electromagnetic wave generator in the world and is designed to test materials in conditions of extreme temperature and pressure. It was original ...
*ZEBRA device at the University of Nevada's Nevada Terawatt Facility
*Saturn accelerator at
Sandia National Laboratory
Sandia National Laboratories (SNL), also known as Sandia, is one of three research and development laboratories of the United States Department of Energy's National Nuclear Security Administration (NNSA). Headquartered in Kirtland Air Force Bas ...
*
MAGPIE
Magpies are birds of the Corvidae family. Like other members of their family, they are widely considered to be intelligent creatures. The Eurasian magpie, for instance, is thought to rank among the world's most intelligent creatures, and is one ...
at
Imperial College London
Imperial College London (legally Imperial College of Science, Technology and Medicine) is a public research university in London, United Kingdom. Its history began with Prince Albert, consort of Queen Victoria, who developed his vision for a cu ...
*COBRA at
Cornell University
Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to teach an ...
*PULSOTRON
Inertial electrostatic confinement
*
Fusor
A fusor is a device that uses an electric field to heat ions to nuclear fusion conditions. The machine induces a voltage between two metal cages, inside a vacuum. Positive ions fall down this voltage drop, building up speed. If they collide in ...
**
List of fusor examples
*
Polywell
The polywell is a proposed design for a fusion reactor using an electric field to heat ions to fusion conditions.
The design is related to the fusor, the high beta fusion reactor, the magnetic mirror, and the biconic cusp. A set of electromagn ...
Magnetized target fusion
*FRX-L
*FRCHX
*
General Fusion
General Fusion is a Canadian company based in Vancouver, British Columbia, which is developing a fusion power device based on magnetized target fusion (MTF). The company was founded in 2002 by Dr. Michel Laberge. The company has more than 200 emp ...
– under development
*
LINUS
Linus, a male given name, is the Latin form of the Greek name ''Linos''. It's a common given name in Sweden. The origin of the name is unknown although the name appears in antiquity both as a musician who taught Apollo and as a son of Apollo who di ...
project
References
See also
*
List of nuclear reactors
A ''list'' is any set of items in a row. List or lists may also refer to:
People
* List (surname)
Organizations
* List College, an undergraduate division of the Jewish Theological Seminary of America
* SC Germania List, German rugby union ...
{{Fusion power
Fusion power
Magnetic confinement fusion devices