Hannover 2016 – scientific programme

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P: Fachverband Plasmaphysik

P 12: Poster Session: Magnetic Confinement

P 12.6: Poster

Tuesday, March 1, 2016, 16:30–19:00, Empore Lichthof

Calibration and Usecases of the Electron Cyclotron Emission diagnostic at Wendelstein 7-X — •Udo Höfel, Matthias Hirsch, Karsten Ewert, Hans-Jürgen Hartfuß, Heinrich Peter Laqua, Torsten Stange, Robert Wolf, and the W7-X Team — Max-Planck-Institut für Plasmaphysik, Greifswald

The world’s largest stellarator, Wendelstein 7-X (W7-X), is equipped with a 140 GHz electron cyclotron resonance heating (ECRH) system providing up to 5 MW absorbed power in the first operation phase OP1.1. The foreseen X2-heating scenario uses the high absorption of the second harmonic extraordinary electron cyclotron waves, which leads on the other hand to a black body electron cyclotron emission (ECE) being proportional to the local electron temperature. ECE is one of the fundamental operating diagnostics and is planned to yield the electron temperature profile from the very first discharges onwards. Unlike most other ECE diagnostics, the 32 channel ECE radiometer diagnostic (with additional 16 channels with higher radial resolution) at W7-X is absolutely calibrated. It is planned to use this diagnostic for intensive studies on electron heat transport in the upcoming operational phases of W7-X. Simple switch-off experiments for the determination of the energy confinement time should already be possible within the first plasma shots. Due to the high temporal and radial resolution the ECE will be used also to determine the power deposition by modulation of the heating gyrotron. If reasonably equilibrated plasma conditions could be generated in the first operational phase (OP 1.1), first studies on electron thermal diffusivity could also be possible.