Publications in Scientific Journals:

A. Mink, E. Wolfrum, M. Dunne, M. Hoelzl, M. Maraschek, R. Fischer, M. Cavedon, G. Harrer, U. Stroth, . ASDEX Upgrade Team:
"Scaling of the toroidal structure and nonlinear dynamics of ELMs on ASDEX Upgrade";
Plasma Physics and Controlled Fusion, 60 (2018), 1250111 - 1250119.

English abstract:
Edge localized modes (ELMs) are magnetohydrodynamic (MHD) instabilities that cause fast
periodic relaxations of the strong edge pressure gradient in tokamak fusion plasmas. Magnetic
pick-up coils allow the extraction of toroidal mode numbers n during the ELM cycle including
the nonlinear crash on ASDEX Upgrade, providing a good comparability to nonlinear 3D MHD
codes. This paper investigates how the mode numbers before and during the ELM crash change
with a variation of plasma parameters. It is found that the toroidal structure size during the crash
is similar to the one existing slightly before and always has a low n= 1-7 range. Furthermore,
in the nonlinear phase of the ELM n does not show a clear trend with most peeling-ballooning
relevant parameters such as normalized pressure gradient, bootstrap current density or
triangularity, whereas a strong decrease of n with edge safety factor q 95 is observed in agreement
with nonlinear modeling in the here investigated high collisionality region. A simple geometric
model is presented, which is capable of explaining the q scaling by existence of ballooned
structures that minimize n.

plasma, edge localized mode, nonlinear, mode number

Created from the Publication Database of the Vienna University of Technology.