TJ-II:Magnetic field

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).

TJ-II: Abs(B)

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

TJ-II: Curvature κ_N

Normal magnetic curvature of the magnetic field, κ_N. Definition:

$\kappa _{N}=\kappa \cdot {\frac {\nabla \psi }{|\nabla \psi |}}$

With this definition, positive values of κ_N are regions where curvature-driven modes are stable.

TJ-II: Local shear, s_local

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

• TJ-II:Magnetic coordinates