Fast equilibrium interpretation on the W7-AS stellarator using function parameterization

Interpretive methods for the calculation of plasma equilibria consistent with experiment are common in tokamak analysis but are generally unsuited to stellarators, due to the computational resources required by current 3-D MHD equilibrium codes. To overcome this, we apply function parameterization techniques to facilitate fast equilibrium recovery on W7-AS. These are used as the basis for a rapid interpretive method of equilibrium reconstruction, whereby the plasma pressure profile is inferred from the spatial to flux transformation implicit in electron pressure profile measurements made with the Thomson scattering diagnostic. This interpretive method produces results of comparable or superior quality to conventional methods, but is many orders of magnitude faster. The scheme is tested against standard simulations of W7-AS discharges.