Coordinate conventions¶

Cylindrical coordinate convention¶

For conversion between cylindrical \((R,\phi,Z)\) and Cartesian \((X,Y,Z)\) coordinates, IMAS follows the ISO 31-11 standard: the origin and Z axis align and the X axis corresponds to \(\phi=0\).

Sign convention¶

\((R,\phi,Z)\) is a right-handed coordinate system, so \(\phi\) is counter-clockwise when seen from above.

\((\rho,\theta,\phi)\) is a right-handed coordinate system, so \(\theta\) is clockwise when looking at the righthand poloidal cross-section from the front.

COCOS¶

This version of the IMAS Data Dictionary corresponds to COCOS = 17 coordinate convention.

The COCOS (Coordinate COnvetionS for 3D current and magnetic fields) conventions are described in detail in: O. Sauter and S.Yu. Medvedev, Computer Physics Communications 184 (2013) 293.

More information is also available on the web page of O. Sauter.

Flux surface average¶

Flux-surface average is defined as described here.