Session GP1 - Poster Session IV.
POSTER session, Tuesday afternoon, October 30
Exhibit Hall B,
The RI-Mode on TEXTOR-94 is a well-established and robust plasma regime, combining simultaneously high confinement (with a quality between ELMy and ELM-free H-Mode confinement), high density (close to or even above the Greenwald limit) and high radiation (up to P_rad/P_tot=95%) in a mantle around the plasma. Most RI-Mode experiments have been performed in D plasmas with D fuelling and a strong correlation is found between the edge neutral pressure and the degradation in confinement with respect to the RI-Mode scaling (\tau_RI=n*P^-2/3). D plasmas fuelled with H, however, show a confinement degradation even when the plasma composition is nearly unchanged and the fuelling rate is much lower compared to their pure D counterparts. In addition with varying H content in the plasma, the confinement degradation observed is given by A_i^0.7, i.e. stronger than the usual A_i^0.5 dependence of the usual scaling expressions.