TEMPERATURE-FLUCTUATIONS AND PLASMA EDGE TURBULENCE IN THE BRAZILIAN TOKAMAK TBR

To investigate the tokamak turbulence, a set of Langmuir probes and a triple probe have been designed and used in the TBR [J. Fusion Energy 12, 529 (1993)] to measure average and fluctuating values of density, potential, and temperature of the plasma edge. The obtained results sh owed a significant influence of the temperature fluctuations in the tr ansport parameters. Namely, taking into account this influence, the de nsity and plasma potential power spectra were obtained, and the turbul ence parameters reevaluated. Furthermore, the computed cross-power-spe ctra showed appreciable linear correlation, and the cross-bispectra sh owed a quadratic mode coupling between temperature fluctuations and ot her quantities. Significant bicoherence between these fluctuations was observed. Finally, for a fluctuation monitored at two probe points, n o preferential direction for energy cascading was detected. (C) 1996 A merican Institute of Physics.