TJ-II:Magnetic field: Difference between revisions
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The complexity of the [[TJ-II]] magnetic field is patent from the following two examples, in which a magnetic field property is mapped onto the last closed [[Flux surface|flux surface]] (configuration 100_44_64). The influence of the [[TJ-II:Coil system|toroidal field coils]] is clearly visible (there are 32 toroidal field coils, leading to the striped pattern), as well as that of the [[TJ-II:Coil system|circular/helical coils]] (continuous red stripe in the toroidal direction in | The complexity of the [[TJ-II]] magnetic field is patent from the following two examples, in which a magnetic field property is mapped onto the last closed [[Flux surface|flux surface]] (configuration 100_44_64). The influence of the [[TJ-II:Coil system|toroidal field coils]] is clearly visible (there are 32 toroidal field coils, leading to the striped pattern), as well as that of the [[TJ-II:Coil system|circular/helical coils]] (continuous red stripe in the toroidal direction in the first two figures below). | ||
[[File:TJ-II AbsB.jpg|800px|thumb|center|TJ-II: Abs(B)]] | [[File:TJ-II AbsB.jpg|800px|thumb|center|TJ-II: Abs(B)]] | ||
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Normal [[Magnetic curvature|magnetic curvature]] of the magnetic field, κ<sub>N</sub>. Definition: | Normal [[Magnetic curvature|magnetic curvature]] of the magnetic field, κ<sub>N</sub>. Definition: | ||
:<math>\kappa_N = \kappa \cdot \frac{\nabla \psi}{|\nabla \psi|}</math> | :<math>\kappa_N = \kappa \cdot \frac{\nabla \psi}{|\nabla \psi|}</math> | ||
With this definition, positive values of κ<sub>N</sub> are stable. | With this definition, positive values of κ<sub>N</sub> are regions where curvature-driven modes are stable. | ||
[[File:TJ-II Local shear.jpg|800px|thumb|center|TJ-II: Local shear, ''s''<sub>local</sub>]] | |||
[[Magnetic shear|Local shear]] of the magnetic field. TJ-II is a low-shear device, meaning the [[Magnetic shear|global shear]] is small; however, the value of the local shear can be quite large. | |||
== See also == | == See also == | ||
* [[TJ-II:Magnetic coordinates]] | * [[TJ-II:Magnetic coordinates]] | ||
Revision as of 10:54, 12 October 2009
The complexity of the TJ-II magnetic field is patent from the following two examples, in which a magnetic field property is mapped onto the last closed flux surface (configuration 100_44_64). The influence of the toroidal field coils is clearly visible (there are 32 toroidal field coils, leading to the striped pattern), as well as that of the circular/helical coils (continuous red stripe in the toroidal direction in the first two figures below).
Absolute value of the magnetic field, |B| (T).
Normal magnetic curvature of the magnetic field, κN. Definition:
With this definition, positive values of κN are regions where curvature-driven modes are stable.
Local shear of the magnetic field. TJ-II is a low-shear device, meaning the global shear is small; however, the value of the local shear can be quite large.