Sensitivity of Thomson Scattering Measurements on Electron Distribution Modeling in Low-Density RFP Plasmas

Abstract

A numerical method which relies on Thomson scattering data for the identification and analysis of electron distributions is presented and discussed; the method is developed within the framework of Bayes probability theory. Use of this method on Reversed Field eXperiment (RFX)-mod low-density data supports the proposition that suprathermal tails cause systematic asymmetries in electron temperature profiles. In the limits of signal and spectral resolution of the diagnostic, a semiquantitative analysis is carried on; the presence of nonthermal (NT) populations is found to be consistent with runaway/slideaway plasma conditions. In low-density discharges NT $e^{-}$ presence is compatible with the presence of kinetic dynamo and can contribute to configuration sustainment.