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
Fusion power is a proposed form of power generation that would generate electricity by using heat from nuclear fusion reactions. In a fusion process, two lighter atomic nuclei combine to form a heavier nucleus, while releasing energy. Devices de ...
, where the lack of complex magnets and a simple geometry may allow the construction of dramatically simpler and less expensive fusion reactors.
The two best studied compact toroids are the
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 ...
and
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). A third configuration, the particle ring, does not appear to have attractive performance.
A CT containment system for plasma asymmetrically toroidally shaped by the containment, was first introduced into thought as a concept by Alfvén. The two examplar types; Field-reversed configuration plasma with a null toroid, firstly, is generally produced by
prolate-theta-pinches with the necessarily existing field condition where the field magnetic bias is in a reversed situation. The second type has a non-null toroid, known as a spheromak configuration,
is similar in arrangement to a
smoke ring. The FRC is also toroidal, but extended into a tubular shape or hollow cylinder. The main difference between the two is that the spheromak contains poloidal (vertical rings) and toroidal (horizontal) magnetic fields, while the FRC has only the poloidal fields and requires an external magnet for confinement. In both cases the combination of electrical currents and their associated magnetic fields result in a series of closed magnetic lines that maintains the ring shape, without the need for magnets in the center of the plasma (unlike a
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 ...
).
Of the two, the FRC naturally has a higher
beta, a measure of fusion economics. However, the spheromak had generated better confinement times and temperatures, and recent work suggests that great advances in performance can be made.
Compact toroids are also similar to the
spherical tokamak
A spherical tokamak is a type of fusion power device based on the tokamak principle. It is notable for its very narrow profile, or '' aspect ratio''. A traditional tokamak has a toroidal confinement area that gives it an overall shape similar to ...
, and many spherical tokamak machines were converted from earlier spheromak reactors.
See also
*
High beta fusion reactor
References
Bibliography
* (''Physics''), "Physics through the 1990s", National Academies Press, 1986
* Charles Hartman
"Fusion-Reactor Aspects of the Compact Torus" Lawrence Livermore Laboratory, 11 March 1981
CR-ENEA Frascati, July 2001
Fusion power
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