Hannover 2016 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 1: Helmholtz Graduate School for Plasma Physices I
P 1.5: Fachvortrag
Montag, 29. Februar 2016, 12:40–13:05, b302
Experimental study of turbulence with the Ultra-fast swept Reflectometer in ASDEX Upgrade — •Anna Medvedeva1, 2, 3, 4, Christine Bottereau3, Marco Cavedon1, Frederic Clairet3, Garrard D. Conway1, Stephane Heureaux2, Diego Molina3, Antonio Silva5, Ulrich Stroth1,4, and AUG Team1 — 1Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, D-85748 Garching — 2Université de Lorraine, Nancy, France — 3CEA, IRFM, St-Paul-Lez-Durance, France — 4Physik-Department E28, Technische Universität München, Garching, Germany — 5IST, Lisbon, Portugal
The experimental documentation of density fluctuations and their dependence on plasma parameters provides insights in the nature of turbulence and its driving parameters. In this contribution we will present measurements on the ASDEX Upgrade tokamak of the turbulence characteristics provided by an ultra-fast swept reflectometer with a time resolution as low as 1 µs. The focus will be on the dynamics in the transition from the Low (L) to the High (H) confinement mode which goes through an intermediate (I) phase where turbulence and shear flows strongly interact. I-phases for various plasma conditions are documented and the density gradient evolution is compared with the turbulence level. This investigation is carried out to discriminate between turbulence-driven zonal flows and neoclassically driven shear flows. In addition we present results on high frequency coherent modes appearing at the plasma edge during the H-mode and their link to MHD events (ELMs). The fast density profile dynamics during the ELM cycle is studied in relation to the local turbulence behavior.