[Zurück]

F. Mink, E. Wolfrum, M. Maraschek, H. Zohm, L. Horváth, E. Viezzer, F. Laggner, M. Dunne, P. Manz, U. Stroth, . ASDEX Upgrade Team:
"Characterization of inter-ELM magnetic oscillations on ASDEX Upgrade";
Poster: 43rd EPS Conference on Plasma Physics, Leuven/Belgium; 04.06.2016; in: "Proceedings 43rd EPS Conference on Plasma Physics, Europhys. Conf. Abstracts", 40A (2016), ISBN: 2-914771-99-1; S. 1 - 4.

Edge localized modes (ELMs) occur as repetitive bursts of magnetohydrodynamic (MHD)
activity in the high-confinement regime (H-mode) of tokamak fusion plasmas and might cause
intolerably high heat fluxes onto the divertor target plates or the first wall in future fusion devices
like ITER [1]. According to the broadly accepted peeling-ballooning (PB) model these
MHD instabilities are driven by the steep edge pressure and current gradients, which are characteristic
for the H-mode [2]. Nevertheless, the process that determines the onset of an ELM
crash is not completely understood. It has been reported from different tokamaks that periodic
MHD activities that might be connected to the ELM crash can be observed with defined toroidal
mode numbers n between ELM bursts [3, 4].
Here the toroidal mode number n of inter-ELM phenomena on ASDEX Upgrade is investigated.
Their development is connected to the development of the transport across the separatrix. Furthermore
the poloidal mode number m is calculated to give an estimate for the radial position in
terms of the safety factor q = m=n.
From linear PB stability analysis higher mode numbers of ELM associated modes are expected
for higher collisionality n . In order to investigate this effect mode numbers were determined
for increasing n in an experiment by increasing the density.