The level of density fluctuations is shown to decrease during ergodic divertor operation in Tore Supra. This decrease of the turbulence is correlated with the onset of a temperature pedestal and a local improvement of the confinement. This pedestal is located close to the electric shear layer, i.e. within a narrow region between the plasma core and the ergodic layer. The onset of such a pedestal explains why the central electron temperature is not changed when the ergodic divertor is switched on, in spite of an ergodic zone where the temperature is low

Recently, plasmas exceeding 4 min have been obtained with lower hybrid current drive (LHCD) in Tore Supra. These LHCD plasmas extend for over 80 times the resistive current diffusion time with zero loop voltage. Under such unique conditions the neoclassical particle pinch driven by the toroidal electric field vanishes. Nevertheless, the density profile remains peaked for more than 4 min. For the first time, the existence of an inward particle pinch in steady-state plasma without toroidal electric field, much larger than the value predicted by the collisional neoclassical theory, is experimentally demonstrated.

`Snakes' are observed in Tore Supra after injection of high velocity solid hydrogen or deuterium pellets ablated inside the q=1 surface. They are detected, immediately after the ablation, as oscillations in the line integrated densities of the central interferometer channels. The corresponding oscillations in the soft X-ray signals detach from the noise about 70 ms later. Snakes survive sawtooth crashes, but are nevertheless affected by them. Variations, during the about 500 ms long lifetime, of the snake radius rs, of the rotation frequency and of the rotation direction are discussed, stressing the effects of the sawtooth crashes. In many snakes rs/r1, where r1 refers to the radius of the q=1 surface, is of the order of 0.5. The snake has an m=1, n=1 helicity, pointing out the problem of the interpretation in terms of current profile. Combined simulations of the snake oscillations in both interferometer and soft X-ray signals have indicated that the impurity (carbon) density inside the snake is much larger than that outside it. Since a change of regime seems to appear about 80 ms after the snake formation on the soft X-ray, it seems plausible that impurity (carbon) accumulation takes place at this time. A stability criterion taking into account both impurity and bootstrap effects is presented; the result agrees with the model proposed by Wesson (1995)