Interplay of Confinement Improvement, Density Peaking and Particle Recycling in the Radiatively Improved Mode

Possible channels for suppression of ion temperature gradient (ITG) instability in radiatively improved (RI) mode through peaking of the plasma density are discussed. An interpretive transport analysis is done which shows that increasing ratio between pinch velocity and diffusivity is of the most importance for the peaking. This validates theoretical models which predict a principle difference in this ratio for cases when transport is dominated by ITG or dissipative trapped electron instability. In transport computations these models allow to reproduce changes in the density profile and pattern of recycling by the L-RI transition.