TJ-II:Magnetic field: Difference between revisions

From FusionWiki
Jump to navigation Jump to search
mNo edit summary
No edit summary
Line 5: Line 5:


[[File:TJ-II Curvature.jpg|800px|thumb|center|TJ-II: Curvature &kappa;<sub>N</sub>]]
[[File:TJ-II Curvature.jpg|800px|thumb|center|TJ-II: Curvature &kappa;<sub>N</sub>]]
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>.  
:<math>\kappa_N = \kappa \cdot \frac{\nabla \psi}{|\nabla \psi|}</math>
Positive values of &kappa;<sub>N</sub> are regions where curvature-driven modes 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>]]
[[File:TJ-II Local shear.jpg|800px|thumb|center|TJ-II: Local shear, ''s''<sub>local</sub>]]

Revision as of 12:14, 12 October 2009

The complexity of the TJ-II magnetic field is patent from the following 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).

TJ-II: Abs(B)

Absolute value of the magnetic field, |B| (T).

TJ-II: Curvature κN

Normal magnetic curvature of the magnetic field, κN. Positive values of κN are regions where curvature-driven modes are stable.

TJ-II: Local shear, slocal

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.

See also