TJ-II:Magnetic field: Difference between revisions

no edit summary
mNo edit summary
No edit summary
Line 1: Line 1:
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 both figures).
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)]]
Line 7: Line 7:
Normal [[Magnetic curvature|magnetic curvature]] of the magnetic field, &kappa;<sub>N</sub>. Definition:
Normal [[Magnetic curvature|magnetic curvature]] of the magnetic field, &kappa;<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 &kappa;<sub>N</sub> are stable.
With this definition, positive values of &kappa;<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]]