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P: Fachverband Plasmaphysik

P 19: Poster II

P 19.8: Poster

Thursday, March 31, 2022, 16:00–17:30, P

Modeling the beam emission Balmer-α spectrum in neutral beam heated plasmas at Wendelstein 7-X — •Sebastian Bannmann, Oliver Ford, Udo Höfel, and Robert Wolf — Max-Planck-Institut für Plasmaphysik, Greifswald, DE

The optimized stellarator Wendelstein 7-X (W7-X) is equipped with a neutral beam injection (NBI) system. Knowledge about the particle and heat deposition of the beam in NBI shots is essential for further plasma physics analysis. The deposition depends on the beam and plasma parameters and information can be provided by measuring the Balmer-α light emitted by excited beam and halo particles. As the whole spectrum is too complex to be unambiguously fitted, a modular Bayesian inference network called Minerva is used. This requires implementing a detailed forward model with which one can infer beam and plasma parameters from the measured spectra. Existing modeling tools deploy Monte-Carlo techniques which is not feasible to use in combination with a Bayesian inference framework. The presented work describes the implementation of an analytical neutral beam and halo model. The possibility of inferring ion temperature profiles from the halo Balmer-α emission and density profiles from the halo and beam emission is investigated.