Wendelstein 7-X reference equilibria
The Wendelstein 7-X (W7- X) magnet system, consisting of 70 superconducting coils, allows to realize and investigate a large amount of various magnetic configurations, which have quite different physical properties. To analyze experimental data, equilibrium calculations are used, first of all for mapping of diagnostic data, or, in other words, to assign measurement values to flux surfaces, characteristic for each individual magnetic configuration. In order to have a common basis for the data analysis, available for internal and external researchers, the central verified collection of pre-calculated Wendelstein 7-X equilibria (reference equilibria) was created. For this purpose the web service platform was used. Equilibrium calculations have been performed with W7-X as-designed coil geometries for experimentally run as well as for only theoretically evaluated configurations with different pressure profiles and beta values (https://de.wikipedia.org/wiki/Plasmabeta). This data collection is constantly enlarged and updated. The Variational Moments Equilibrium Code, internally available as a Wendelstein 7-X web service (http://webservices.ipp-hgw.mpg.de/docs/vmec.html) was employed for these calculations. For each specific calculation representation of magnetic flux surfaces (http://fusionwiki.ciemat.es/wiki/Flux_surface) as well as profiles of rotational transform (http://fusionwiki.ciemat.es/wiki/Rotational_transform), plasma pressure and effective helical ripple ɛeff , characterizing confinement properties, are generated. Further characteristic values (e.g. magnetic surface radii, position of the last closed flux surface for a given toroidal angle, kinetic energy etc.), can be also viewed in the browser or obtained in a programmatic way with help of web service requests.