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This paper reports on a simulation of reflectometry measurement in Tore Supra ohmic discharges, for which the experimental observations as well as gyrokinetic non-linear computations predict a modification of turbulence spectrum between the linear (LOC) and the saturated ohmic confinement (SOC) regimes. Synthetic reflectometry simulations coupling full-wave computations with gyrokinetic data are carried out. This allows a direct comparison between the gyrokinetic non-linear predictions and experimental observations. The synthetic diagnostic results are found in a good agreement with the experimental findings; in particular, they reproduce well the quasi-coherent peak in the fluctuation spectrum of LOC regimes dominated by a trapped electron mode turbulence. It is also shown that such synthetic tools are valuable for (i) an enhanced interpretation of the reflectometry measurement (for instance, through the investigation of the 2D effects) and (ii) a better understanding of the turbulence properties (for instance, via the analysis of its poloidal asymmetry). [ABSTRACT FROM AUTHOR]

In a dedicated collisionality scan in Tore Supra, the geodesic acoustic mode (GAM) is detected and identified with the Doppler backscattering technique. Observations are compared to the results of a simulation with the gyrokinetic code GYSELA. We found that the GAM frequency in experiments is lower than predicted by simulation and theory. Moreover, the disagreement is higher in the low collisionality scenario. Bursts of non harmonic GAM oscillations have been characterized with filtering techniques, such as the Hilbert-Huang transform. When comparing this dynamical behaviour between experiments and simulation, the probability density function of GAM amplitude and the burst autocorrelation time are found to be remarkably similar. In the simulation, where the radial profile of GAM frequency is continuous, we observed a phenomenon of radial phase mixing of the GAM oscillations, which could influence the burst autocorrelation time. [ABSTRACT FROM AUTHOR]