Turbulence in the TORE SUPRA Tokamak: Measurements and Validation of Nonlinear Simulations

Turbulence measurements in TORE SUPRA tokamak plasmas have been quantitatively compared to predictions by nonlinear gyrokinetic simulations. For the first time, numerical results simultaneously match within experimental uncertainty (a) the magnitude of effective heat diffusivity, (b) rms values of density fluctuations, and (c) wave-number spectra in both the directions perpendicular to the magnetic field. Moreover, the nonlinear simulations help to revise as an instrumental effect the apparent experimental evidence of strong turbulence anisotropy at spatial scales of the order of ion-sound Larmor radius.

Figure 1

Radial profile of the experimental effective heat diffusivity and comparison with the GYRO predictions.

Figure 2

Radial profile of the experimental rms $\delta n/n$ and comparison with the GYRO predictions.

Figure 3

Experimental density fluctuation $k_{\theta }$ spectrum at $r/a=0.7$, and comparison with the GYRO and GYSELA predictions.

Figure 4

Experimental density fluctuation $k_r$ spectrum at $r/a=0.7$, and comparison with the GYRO predictions.

Figure 5

(a) $|\delta n/n{|}^2$ spectra from the GYRO simulation at $r/a=0.7$, and the impact of reconstructing the Doppler reflectometry instrumental response on the $k_{\theta }$ spectrum. (b) Contour plot of the GYRO ${log}_{10}|\delta n(k_r,k_{\theta })/n{|}^2$.