VMEC

The three-dimensional Variational Moments Equilibrium Code (VMEC) minimizes the energy functional

$W=\underset{{\omega }_p}{\int }(\frac{1}{2{\mu }_0}{B}^2+p)dV$

over the toroidal domain ω_p. The solution is obtained in flux coordinates (s, θ, ζ), related to the cylindrical coordinates (R, φ, Z) by

$R=\sum R_{mn}(s)\cos (m\theta -n\zeta )$

$Z=\sum Z_{mn}(s)\sin (m\theta -n\zeta )$

The code assumes nested flux surfaces.

Implementations of the code

The code is being used at:

• ORNL, Oak Ridge, TN, USA (code origin)
• IPP, Garching, Germany
• CRPP, Lausanne, Switzerland
• NIFS, Japan
• LNF, Spain

Enhancements / extensions of the code

• DIAGNO, to calculate the response of magnetic diagnostics
• MFBE
• STELLOPT