Erlangen 2018 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 11: Helmholtz Graduate School - Poster
P 11.5: Poster
Dienstag, 6. März 2018, 16:15–18:15, Redoutensaal
Beam asymmetry and homogeneity characterization at the large negative ion source ELISE — •Isabella Mario, Dirk Wünderlich, Ursel Fantz, and Federica Bonomo — Max-Planck-Institut für Plasmaphysik, Garching, Germany
The ITER neutral beam injection (NBI) system is based on RF sources for production of negative ions (H−/D−). The ELISE test facility (source size is half the size of the source for ITER NBI) is an intermediate step in the European R&D roadmap towards the full size ITER source. The aim of ELISE is to fulfill the basic ITER requirements regarding extracted ion current, electron ion ratio at low filling pressure (≤ 0.3 Pa) up to one hour pulse. On the beam side, at the exit of the acceleration stage, local maximum deviation from the averaged beam power density must be less than 10% in order to ensure good beam line transmission. For ELISE, with a beam of about 1 m2, the lowest achievable beam divergence is about 17 mrad and vertical asymmetry and inhomogeneity are mainly caused by the interplay of plasma drift, non-uniform negative ion production as well as beam deflection by magnetic field. Aim of this work is to improve the understanding of the correlation between locally resolved beam properties with global electrical measurements from beamline components and source parameters. For this purpose we make use of two beam diagnostics: beam emission spectroscopy placed at 2.7 m downstream the extraction system, with a vertical resolution of 5 cm, and the infrared calorimetry on a diagnostic calorimeter at 3.5 m, with a resolution of 4 cm. Both diagnostics provide beam divergence and accelerated current.