Göttingen 2025 – scientific programme

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P: Fachverband Plasmaphysik

P 17: Poster Session II

P 17.47: Poster

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

Towards a standard Diagnostic for not absorbed Electron Cyclotron Resonance Heating power at Wendelstein 7-X — •Jonas Zimmermann, Torsten Stange, Heinrich Laqua, Dmitry Moseev, and Johan Oosterbeek — IPP Greifswald

Electron cyclotron resonance heating (ECRH) at 140 GHz is the primary heating method of the Wendelstein 7-X device, a magnetically confined plasma experiment with the goal to demonstrate 30 minute plasma operation. Gaussian beams, with a power of about 1 MW each, are radially injected into the plasma, propagate as plasma waves, and are absorbed at the resonance where their frequency matches the 2nd harmonic of the electron cyclotron frequency. Non-absorbed radiation leaves the plasma and hits the wall opposite to the ECRH launchers. During long pulse operation, even a small percentage of non-absorbed power is sufficient to cause critical head loads on directly hit components. Therefore, a primary objective is to deposit the power only in the plasma and to guarantee the optimal parameters for polarization and direction of the beam. The wall opposite to the ECRH launchers is equipped with an antenna array called Electron Cyclotron Absorption (ECA) diagnostic, capable of detecting the power density and sensitive to the polarization of the transmitted beams. It is planned to use this diagnostic to routinely measure the fraction of non-absorbed power caused by various plasma effects or incorrect beam parameterization. This poster presents initial results of the ECA diagnostic on absorption, refraction, and beam parameter changes, and outlines steps toward a quantitative absorption diagnostic.

Keywords: ECRH; Heating