München 2019 – wissenschaftliches Programm
P 18.107: Poster
Donnerstag, 21. März 2019, 16:30–18:30, Foyer Audimax
Experimental Study of the Influence of the Scrape-off Layer Radial Electric Field on the Transition to the High Confinement Mode — •Ulrike Plank1,2, Thomas Pütterich1,2, Marco Cavedon1, Elisabeth Wolfrum1, Ulrich Stroth1, and The ASDEX Upgrade Team1 — 1MPI für Plasmaphysik, Garching, Germany — 2Ludwig-Maximilian-Universität, München, Germany
The high confinement mode (H-mode) is a state of improved plasma confinement in diverted tokamaks. It is achieved when the input power exceeds a threshold and it exhibits a transport barrier in the edge of the confined plasma region. This transport barrier is considered to be caused by local gradients in the radial electric field (Er) at the edge of the confined plasma region, which lead to sheared E × B flows (vE × B). These flows suppress turbulent transport in the edge, resulting in an improved plasma confinement. On ASDEX Upgrade (AUG) it was found that a critical value for the vE × B minimum, a proxy for the vE × B shear, is needed to sustain H-mode. However, the power threshold to enter H-mode changes when the conditions at the plasma boundary, i.e. in the scrape-off layer (SOL), are altered. Modeling results indicate that these effects impact the magnitude of Er in the SOL. Therefore, Er in the SOL could influence the gradients of Er in the confined region and the access to H-mode. In order to experimentally access Er in the SOL a charge exchange recombination spectroscopy diagnostics was installed in AUG. First experimental results will be presented.