[Zurück]

S. Rathgeber, L. Barrera Orte, R. Fischer, W. Suttrop, M. Willensdorfer, E. Wolfrum, . ASDEX Upgrade Team:
"Investigations on kinetic edge profiles and their gradients of magnetically perturbed ASDEX Upgrade plasmas";
in: "Proc. 39th EPS Conference on Plasma Physics", EPS, 36F, 2012, ISBN: 2-914771-79-7, S. 1 - 4.

The intended operation scenario for ITER, the High-confinement mode (H-mode), is accompanied
by type-I Edge Localized Modes (ELMs). The power flux along the open field lines in
the scrape-off layer during these ELMs may likely exceed the critical limit of the divertor plates.
At ASDEX Upgrade, non-axisymmetric Magnetic Perturbation (MP) of the plasma edge by external
coils has been proven to enable ELM mitigation and, therefore, effectively reduce the
peak power load on the target [1]. To improve the understanding of the underlying mechanism
in order to assess the possibility of ELM mitigation with MP at ITER, detailed analysis about
its effect on plasmas under diverse conditions is necessary.
Since ELMs are supposed to be related to high edge pressure gradients according to peelingballooning
theory, the influence of MP on the electron edge kinetics might be essential for
ELM mitigation. A suitable tool to study these is provided by Integrated Data Analysis (IDA)
of different diagnostics for simultaneous analysis of the electron density and temperature [2]
and, therefore, also the pressure. However, previous investigations of perturbed edge profiles
concentrated on the electron density [3] because IDA was lacking a reliable interpretation of
the Electron Cyclotron Emission (ECE) data for the electron temperature reconstruction in the
edge gradient region. Recently, IDA has been enhanced by a sophisticated model for ECE which
delivers reliable edge electron temperature profiles with high spatial resolution [4]. Based on
these results, a thorough investigation on the kinetic edge profiles and their gradients - with
emphasis on electron temperature and pressure - of discharges with perturbed magnetic field
has been started. In this contribution we present first results which demonstrate slightly lower
edge electron kinetic gradients in the presence of MP.