Electron density profile reconstruction on the TCABR sweeping reflectometer

A Frequency Sweeping Reflectometry System is under re-installation in the TCABR tokamak to provide the electron density profiles in this machine. This diagnostic operates in a frequency range between 18 GHz and 40 GHz, in Ordinary (O-mode) or in Extraordinary (X-mode) polarization modes. This diagnostic can cover electron densities between 0.4×1019m-3 and 2.0×1019m-3, when configured in O-mode. Electron density profiles can be inferred from the phase dependence of the probing frequency, dΦ(f) df, measured at the output of the reflectometer system. To evaluate the measuring capabilities and the requirements for using a frequency sweeping reflectometer, a numerical method to reconstruct the density profiles in the TCABR tokamak was implemented. The robustness of inversion method was tested through the following steps: i) Determination of dΦ(f) df from a known density profile; ii) Reconstruction of the electron density profile by the method that will be presented here; iii) Comparison between the original and reconstructed electron density profiles to test the validity of the method. The method and analysis are applied for the X and O polarization modes. These computational analyses can be useful for the interpretation of reflectometer diagnostic data and the experimental data can be used to check the validity of the numerical model.