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P: Fachverband Plasmaphysik

P 6: Helmholtz Graduate School I

P 6.2: Poster

Montag, 13. März 2017, 16:30–18:30, HS Foyer

Influence of pedestal top properties on ELM mitigation and first insights into the pump-out effect — •Nils Leuthold¹, Wolfgang Suttrop¹, Rainer Fischer¹, Athina Kappatou¹, Andrew Kirk², Rachael McDermott¹, Alexander Mlynek¹, Martin Valovic², Matthias Willensdorfer¹, the ASDEX Upgrade Team¹, and the EUROfusion MST1 Team³ — ¹Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany — ²CCFE, Culham Science Centre, Abingdon, Oxon, OX14 3DB, U.K. — ³See http://www.euro-fusionscipub.org/mst1

Edge Localized Modes (ELMs) are triggered by the steep edge gradients, which get formed in the high confinement mode of a tokamak device. They expell particles and energy in a burst like manner. While controlable ELMs provide a useful tool to avoid impurity accumulations, it is essential to find ways to mitigate or suppress ELMs in the next step fusion device ITER in order to reduce the harmful energy fluence to the first target. One encouraging method is the application of a magnetic perturbation (MP) field, but along with the ELM mitigation/suppression by the MPs comes also the so called "density pump-out" effect. It is triggered by the MPs and causes a degradation of the plasma confinement by expelling a significant amount of the particle inventory. The influence of the electron density and collisionality at the top of the H-mode pedestal on the energy losses caused by ELMs is shown as well as a first insight into the pump-out effect. An approach to test various theories regarding the pump-out effect on ASDEX Upgrade is presented.