Observation and Modelling of the Onset of Parametric Decay Instabilities during Gyrotron Operation at ASDEX Upgrade
Max-Planck-Institut für Plasmaphysik Boltzmannstraße, D-85748 Garching b. München Germany
2 Department of Physics, Technical University of Denmark, Fysikvej, DK-2800 Kgs. Lyngby, Denmark
3 See Appendix in A. Kallenbach for the ASDEX Upgrade Team and the EUROfusion MST1 Team Nucl. Fusion 57 102015 (2017)
* e-mail: Soeren.Kjer.Hansen@ipp.mpg.de
Published online: 25 March 2019
We investigate parametric decay instabilities (PDIs) occurring for gyrotron radiation near the upper hybrid resonance at the ASDEX Upgrade tokamak. The PDIs are observed through anomalous millimeter-wave scattering which is recorded using the high-resolution, fast acquisition collective Thomson scattering system installed at ASDEX Upgrade, and an experiment in which such observations are made during a scan of the toroidal magnetic ﬁeld is performed. A previously published theoretical model is used to calculate the gyrotron power necessary to excite PDIs in the experiment; the theoretical model is capable of predicting whether or not PDIs will be observed at a given toroidal magnetic ﬁeld with a high degree of accuracy.
© The Authors, published by EDP Sciences, 2019
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