Spatial and temporal analysis of DIII-D 3D magnetic diagnostic data

An extensive set of magnetic diagnostics in DIII-D is aimed at measuring non-axisymmetric “3D” features of tokamak plasmas, with typical amplitudes ∼10−3 to 10−5 of the total magnetic field. We describe hardware and software techniques used at DIII-D to condition the individual signals and analysis to estimate the spatial structure from an ensemble of discrete measurements. Applications of the analysis include detection of non-rotating MHD instabilities, plasma control, and validation of MHD stability and 3D equilibrium models.