Heat transport and turbulence in TORE SUPRA Ohmic discharges

Transport analyses and fluctuation measurements have been made in TORE SUPRA Ohmic discharges to investigate the origin of energy confinement time saturation. No major changes in ion heat transport nor any onset of an ion turbulence are observed to appear at the saturation point of the confinement time, which then seems to be governed by the electrons. With the hypothesis of pure electronic turbulence, the persistent ion feature observed in the turbulence spectra may be due to a Doppler shift linked to an inversion of the radial electric field near the edge of the plasma. (author). 4 refs, 4 figs