München 2019 – wissenschaftliches Programm
P 18.90: Poster
Donnerstag, 21. März 2019, 16:30–18:30, Foyer Audimax
Correlation between source parameter and beam properties at the large negative ion source ELISE — •Isabella Mario, Federica Bonomo, Ursel Fantz, and Dirk Wünderlich — Max-Planck-Institut für Plasmaphysik, Garching, Germany
The neutral beam injection (NBI) system for ITER is based on RF sources for production of negative ions (H−/D−). In the European R&D roadmap towards the full size ITER NBI source, the ELISE test facility with half the size of the ITER NBI source aims 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. The ITER beam requirement in term of beam uniformity (>90%) ensures good beam line transmission. The large (1 m2) beam produced at the ELISE test facility can be vertically asymmetric and inhomogeneous due to the interplay of plasma drifts and non-uniform negative ion production and extraction. Aim of this work is to correlate the plasma properties in the region close to the extraction system with the beam in order to improve the insight into physical effects affecting the beam properties. Particular emphasis is laid on vertical profiles both in the source and on the beam side. The main plasma parameters such as positive ion density, plasma potential, negative ion density and caesium density are monitored at 2 cm distance from the extraction apertures. The beam losses into the grid system and the global extracted current are electrically measured while several beam diagnostic tools provide local accelerated beam currents and local beam divergences.