Two-dimensional effects of turbulence in density profile measurements by reflectometry

A code, based on the WKB two-dimensional approximation, is used to simulate the reflectometry measurements in a turbulent plasma. Fixed frequency simulations both for W7-AS and ITER parameters show an increase in perturbations due to two-dimensional turbulence as the dominant wavelength becomes shorter. In larger devices the perturbation is stronger for a given turbulence level and size. Density profile measurements are simulated for ITER using pulse radar amplitude modulation (AM) and frequency modulation (FM) reflectometers. Using some level of averaging (which includes the signal amplitude to average the time delay) the different techniques give reconstructed profiles which are in good agreement with the average of the actual density profile. Results for different levels of turbulence are also shown. (Author)