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P: Fachverband Plasmaphysik
P 12: Magnetic Confinement / Plasma Wall Interaction I
P 12.2: Talk
Wednesday, March 30, 2022, 14:15–14:30, P-H12
Scaling Behavior of the Weakly Coherent Mode in ASDEX Upgrade I-mode Plasmas — •Manuel Herschel1,2, Tim Happel1, Joey Kalis1,3, Gregor Birkenmeier1,3, Michael Griener1, Klara Höfler1,3, and The ASDEX Upgrade Team1 — 1MPI für Plasmaphysik, Garching, Germany — 2Universität Ulm, Germany — 3Physik Department E28, TUM, Garching, Germany
Improved confinement regimes are fundamental in the operation of current and future fusion devices. Among these regimes, the I-mode combines the beneficial properties of an H-mode like energy confinement with the absence of ELMs. The physical origin of the I-mode is still not fully understood, but the so-called weakly coherent mode (WCM) dominant in the turbulence spectrum at the plasma edge is often considered to be a key player for I-mode.
To investigate the WCM in detail, turbulence measurements from multiple diagnostics (Doppler reflectometry, thermal helium beam emission spectroscopy) on ASDEX Upgrade are combined in order to characterize the mode better. These measurements include the radial localization, frequency and wavenumber of the WCM, along with important local plasma parameters such as the magnetic field strength, density and temperature.
To ensure statistical significance and enable comparisons over multiple discharges, these measurements are collected in a database consisting of various I-mode plasmas. With this database, the scaling of parameters of the WCM depending on typical plasma variables is examined and compared with proposed theories.