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P: Fachverband Plasmaphysik

P 5: Poster Session- Helmholtz Graduate School for Plasma Physics

P 5.21: Poster

Montag, 29. Februar 2016, 16:30–19:00, Empore Lichthof

Optimization of ECR wave polarization for improved heating efficiency — •Ihor Vakulchyk and Nikolai Marushchenko — Max Planck Institute for Plasma Physics, Wendelsteinstr. 1, D-17491 Greifswald, Germany

The propagation of electromagnetic waves in an inhomogeneous magnetized plasma is accompanied by continuous power pumping from the main wave mode (ordinary or extraordinary) to another one. When the mode purity has decreased noticeably, this leads to a deterioration of ECRH efficiency and changes of the deposition profile. The purpose of this work is to determine the initial parameters of the wave polarization providing a minimum of spurious modes and to estimate the theoretical limit of the wave-mode purity for ECRH in realistic 3D stellarator plasmas. A preliminary model for the evolution of the wave polarization and the wave-mode coupling is formulated and compared with simplified analytical 2D magnetic field model. A comparison with existing models is found to be satisfactory. The model is applied also to a typical 3D magnetic configuration of the W7-X stellarator. The final aim of the work is the implementation of the model in existing numerical tools for experimental modelling.