Full performance ECRH experiments at W7-AS

The last experimental campaign at W7-AS took advantage of the full designed ECRH power. Together with the high flexibility of the experimental setup, this allows for new sophisticated experimental scenarios which will be described. With central ECRH deposition of 2.1 MW power a record electron temperature of 6.5 keV has been reached with a strongly peaked temperature profile. It has been shown that the confinement improves significantly due to the radial electric field (''electron root'') induced by ECRH driven particle losses. The limits of the linear theory were demonstrated in high power ECRH experiments. The power transmitted through the plasma is reduced by an order of magnitude due to a suprathermal population generated from HFS launch. The dynamic behavior of the EC driven current was investigated in order to develop an adaptive feedback current control for ECCD