Experimental investigation of reflectometry as a density fluctuation diagnostic

In this paper, a controlled laboratory experiment to investigate the response properties of reflectometry to the density fluctuations is presented. The reflectometer signal is observed to be highly spatially localized in the plasma. The quantitative measurement has demonstrated that the signal originates about one free space wavelength of the probe wave in front of the critical layer and this position is independent of the fluctuation wavenumber. It is also found that the sensitivity of transverse response to wavenumbers is different from that of longitudinal response.