Hannover 2020 – scientific programme

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P: Fachverband Plasmaphysik

P 16: Poster Session 3

P 16.9: Poster

Wednesday, March 11, 2020, 16:30–18:30, Empore Lichthof

Statistical analysis of ballooning effect for sawtooth crashes in ASDEX Upgrade — •Oleg Samoylov, Valentin Igochine, Branka Vanovac, Matthias Willensdorfer, Hartmut Zohm, and ASDEX Upgrade Team — Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany

Sawtooth oscillations are nonlinear periodic relaxations of core plasma density and temperature in tokamaks. While the oscillations are often observed and known for decades, the process by which the periodic collapse of the core plasma temperature occurs is still only partially understood. There is no final model that could fully describe all experimental measurements. Some of the proposed sawtooth models predict a higher rate of the crashes at the low field side due to the ballooning effect. To prove the hypothesis, we statistically study the occurrence of the crashes at the low field side in ASDEX Upgrade. The main diagnostic for this study was 2D electron cyclotron emission (ECE) diagnostic, which measured temperature perturbations at the q=1 magnetic surface at the low field side. 200 sawtooth crashes were analyzed. 39 % of the sawtooth crashes were observed in the 2D ECE window, whereas in case of symmetrical occurrence only 23.6 % crashes were expected. This shows weak ballooning effect for the crashes used in the studies.