Confinement and transport in EC heated RI-mode discharges in TEXTOR

This paper reports on experiments in TEXTOR with electron cyclotron resonance heating (ECRH) of radiatively improved (RI) mode discharges. With ECRH the energy content of RI-mode discharges can be increased without the normally observed power degradation in confinement time. The experiments are described and the effects of ECRH on global confinement and local plasma parameters of RI-mode discharges are discussed; the favourable scaling of energy content is due to a zone of low electron thermal transport just outside the sawtooth inversion radius. Moreover, the heating effect of ECRH in the RI-mode is compared with the effect in L-mode; this comparison sheds some light on the physics of electron thermal transport in RI-mode discharges.