Turbulent transport studies in the JET edge plasmas in limiter configuration

Electrostatic turbulence has been investigated in the plasma boundary region of the JET tokamak. The normalized fluctuation levels are in the range of 10-20% at the plasma radius where the poloidal velocity of the fluctuation reverses sign. In limiter plasmas, the E x B turbulent transport can account for a significant part of the total particle and energy losses. Three regions in the power spectra of the fluctuations with different frequency dependences have been found. The spectral region with power decay close to 1/f has been identified in the frequency range where the turbulent flux, which comes in bursts, is dominant. This result could be an indication of transport close to instability thresholds.