Bremen 2017 – wissenschaftliches Programm
P 13.11: Poster
Dienstag, 14. März 2017, 16:30–18:30, HS Foyer
Influence of the Neutral Velocity Distribution on the Results of Pedestal Transport Modeling — •Johannes Gnilsen1, Florian Laggner1, Sebastian Keerl1, Elisabeth Wolfrum2, Emiliano Fable2, Gregor Birkenmeier2, and Eleonora Viezzer3 — 1Institut für Angewandte Physik, TU Wien, 1040 Vienna, Austria — 2Max-Planck- Institut für Plasmaphysik 85748 Garching, Germany — 3Department of Atomic, Molecular and Nuclear Physics, Universidad de Sevilla, 41012 Spain
High confinement mode operation in tokamak plasmas is accompanied by periodically appearing collapses of the edge transport barrier (pedestal) and a burst-like ejection of particles and energy, called edge localized modes (ELMs). After each ELM, both, the electron density and temperature recover and the pedestal builds up again. The temporal evolution of the density recovery is modeled using the transport code ASTRA, which solves the continuity equation for the tokamak geometry. Experimentally measured profiles are modeled interpretatively by adapting the profile of the diffusion coefficient. At the plasma edge the ionization of neutrals causes a significant source of plasma particles, which strongly contributes to the density build-up. This work will investigate the influence of assumptions made on the neutral velocity distribution on the diffusion coefficients derived from ASTRA modeling. Diffusion coefficients obtained from simulations with purely thermal neutrals will be compared to results using distributions with higher velocities, which stem from e.g. Franck-Condon decay or direct reflection from high-Z walls.