Göttingen 2025 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

P: Fachverband Plasmaphysik

P 17: Poster Session II

P 17.25: Poster

Wednesday, April 2, 2025, 16:15–18:15, ZHG Foyer 1. OG

Modeling of the spatial and temporal dynamics of Cs in large negative hydrogen ion sources using the CsFlow3D code — •Daniele Mussini, Adrian Heiler, Christian Wimmer, Dirk Wünderlich, and Ursel Fantz — Max-Planck-Institut für Plasmaphysik (IPP), Boltzmannstr. 2, 85748 Garching

Negative ion-based sources for ITER's neutral beam injectors (NBI) rely on the production of negative hydrogen ions on a low work function converter surface (plasma grid, PG). To reduce the work function of the PG (< 2eV), Cs is continuously evaporated into the source forming a layer on the PG. However, the plasma-surface interaction and the resulting redistribution of Cs inside the source lead to a temporally unstable and inhomogeneous layer. This is a key aspect to be investigated and understood in order to perform long pulses at ITER's requirements (several hundred s in H, 3600s in D). For this purpose, the Monte-Carlo Test-Particle code CsFlow3D is exploited. CsFlow3D models the Cs dynamics in the source, for which several input parameters (plasma parameters, electromagnetic fields, sticking coefficients, etc.) are required. The current target is to model the Cs dynamics during long pulses for the BATMAN Upgrade source in hydrogen. To validate the code, a synthetic laser absorption diagnostic (TDLAS) for the quantification of neutral Cs densities along different line-of-sights is implemented to compare to experimental results. This contribution presents the results of the code after the implementation of input parameters resulting from a fluid code and the benchmark of the code against experimental TDLAS results.

Keywords: Cs; CsFlow3D; TDLAS; ITER; IPP