Erlangen 2018 – scientific programme

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P: Fachverband Plasmaphysik

P 11: Helmholtz Graduate School - Poster

P 11.6: Poster

Tuesday, March 6, 2018, 16:15–18:15, Redoutensaal

Magnetic field configurations for reducing co-extracted electrons from an ITER NBI relevant ion source. — •Ivar Mauricio Montellano, S. Mochalskyy, D. Wünderlich, and U. Fantz — Max- Planck-Institut für Plasmaphysik, 85748 Garching, Germany

The ITER NBI system is based on powerful large-scale RF sources for negative hydrogen or deuterium ions. In order to improve the insight into the complex physics of the low pressure, low temperature plasma close to the extraction system of the ion source the application of self-consistent models is mandatory. The presence of two different magnetic fields, the filter field and the electron deflection field, which are perpendicular to each other, breaks the symmetry of the system making the application of a 3D model necessary. The 3D Particle in cell (PIC) code ONIX is capable to simulate the plasma volume close to one extraction aperture of the ITER prototype source. So far, ONIX has been applied in order to reproduce the generation and extraction of negative hydrogen ions and of co-extracted electrons. Of particular importance is the ratio of co-extracted electron current to extracted ion current which has to be kept below one for ITER. In the experiment several parameters can be modified to reduce and stabilize the co-extracted electrons, for example the strength topology of the magnetic fields. In order to improve the physical insight and as first step towards predictive calculations, different magnetic field configurations are simulated with ONIX to determine their effect in the co-extracted electron current. Presented are the results of these simulations and the discussion about the influence of different magnetic field configurations.