Greifswald 2024 – scientific programme

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P: Fachverband Plasmaphysik

P 25: Poster III

P 25.20: Poster

Thursday, February 29, 2024, 16:30–18:30, ELP 6: Foyer

Spatially and temporally resolved simulations of the Cs dynamics in large negative hydrogen ion sources assisted by TDLAS measurements — •Daniele Mussini, Adrian Heiler, Dirk Wünderlich, and Ursel Fantz — Max-Planck-Institut für Plasmaphysik (IPP), Boltzmannstr. 2, 85748 Garching

Negative hydrogen ion sources for the ITER neutral beam injectors rely on the production of negative hydrogen ions on a low work function surface (plasma grid). To reduce the surface work function, a Cs layer is formed on the plasma grid by steadily evaporating Cs into the source. However, mainly due to plasma-surface interaction and Cs redistributions, it is not straightforward to generate a temporally stable and homogeneous Cs layer. In particular, this is a major challenge for the long pulse operation required for ITER (1000 s in H, 3600 s in D). To gain insight into the Cs dynamics by numerical modeling, the Monte-Carlo Test-particle code CsFlow3D was developed at IPP. The code uses many input parameters such as EM fields, plasma temperature and density profiles to determine the Cs dynamics within sources of different sizes. The current main objective is to investigate the Cs behavior during long pulses for both H or D operation. To do so, an updated version of input parameters must be implemented. In addition, the synthetic laser absorption diagnostic (TDLAS) needs to be simulated to benchmark the code against experimental results. This contribution is intended to show some preliminary results and to provide an outlook on future steps for the further development and improvement of the code.

Keywords: Cs; CsFlow3D; TDLAS; ITER; IPP