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S. Rathgeber, L. Barrera Orte, T. Eich, R. Fischer, B. Nold, W. Suttrop, M. Willensdorfer, E. Wolfrum, . ASDEX Upgrade Team:
"Estimation of edge electron temperature profiles via forward modelling of the electron cyclotron radiation transport at ASDEX Upgrade";
Plasma Physics and Controlled Fusion, 55 (2013), 0250041 - 02500415.

We present a method to obtain reliable edge profiles of the electron temperature by forward
modelling of the electron cyclotron radiation transport. While for the core of ASDEX Upgrade
plasmas, straightforward analysis of electron cyclotron intensity measurements based on the
optically thick plasma approximation is usually justified, reasonable analysis of the steep and
optically thin plasma edge needs to consider broadened emission and absorption profiles and
radiation transport processes. This is carried out in the framework of integrated data analysis
which applies Bayesian probability theory for joint analysis of the electron density and
temperature with data of different interdependent and complementary diagnostics.
By this means, electron cyclotron radiation intensity delivers highly spatially resolved
electron temperature data for the plasma edge. In H-mode, the edge gradient of the electron
temperature can be several times higher than the one of the radiation temperature.
Furthermore, we are able to reproduce the `shine-through´ peak-the observation of increased
radiation temperatures at frequencies resonant in the optically thin scrape-off layer. This
phenomenon is caused by strongly down-shifted radiation of Maxwellian tail electrons located
in the H-mode edge region and, therefore, contains valuable information about the electron
temperature edge gradient.