Integrated software for the analysis of high-resolution scattering signals during mm-wave beam injection

Abstract

Recently, during Collective Thomson Scattering (CTS) measurements at mm-waves aimed at studying the ion dynamics in fusion plasmas, strong signals of scattering of the injected beam with non-CTS origin have been detected. A possible explanation of these signals in terms of parametric decay instabilities (PDIs) of the injected wave with power threshold much lower than previously envisaged by theory was proposed [1,2]. The experimental activity with CTS diagnostic at FTU is aimed at two purposes: the characterization of the thermal ion distribution function and the investigation of the possible low power PDIs processes foreseen by the recent models. In order to ease the data analysis, a set of data processing tools has been integrated on purpose, with an activity started in 2014. Here we present the last implementation of an integrated data analysis tool, aimed at the investigation of the signals detected with the CTS diagnostic. The last version of the software integrates information included in the raw spectra of scattered radiation with the modeled ECE emission, with the aim of providing calibrated spectra improved with respect to the ones provided up to now. The correct calibration of the signals on the real line of sight of the beams is helpful to better distinguish anomalous emissions from less powerful CTS radiation. In addition, the analysis tool compares the calibrated spectra with the ones predicted considering real scattering parameters evaluated by means of realistic beam-trajectories, changing during the pulse, allowing also to extract information on ion dynamics and plasma composition. The last version of the software, which takes into account also multi-reflection beam-tracing simulations in both polarization modes in support to the scattering experiments, is presented.