Multi-Instrument Bayesian Reconstruction Of Plasma Shape Evolution In The C-2w Experiment

We determined the time-dependent geometry, including high-frequency oscillations, of the plasma density in TAE's C-2W experiment [Gota et al., Nucl. Fusion 59, 112009 (2019)]. This was done as a joint Bayesian reconstruction from a 14-chord FIR interferometer in the midplane, 32 Mirnov probes at the periphery, and 8 shine-through detectors at the targets of the neutral beams. For each point in time, we recovered, with credibility intervals, the radial density profile of the plasma; bulk plasma displacement; and amplitudes, frequencies, and phases of the azimuthal modes n = 1,., 4. Also reconstructed were the radial profiles of the deformations associated with each of the azimuthal modes. Bayesian posterior sampling was done via Hamiltonian Monte Carlo with custom preconditioning. This gave us a comprehensive uncertainty quantification of the reconstructed values, including correlations and some understanding of multimodal posteriors. Published under an exclusive license by AIP Publishing.