Single shot, non-resonant, four-wave mixing laser diagnostics for low and high temperature plasmas

We present our recent experimental and theoretical work in utilizing intense optical lattices for the thermodynamic characterization of different species (neutrals, ions, electrons and nanoparticles) in low and high temperature plasmas. At the core of our study is the use of single shot coherent Rayleigh-Brillouin scattering (CRBS), a four-wave mixing technique, for the measurement of the velocity distribution function (VDF) of these species. The use of single shot CRBS for the characterization of neutral species in a glow discharge has already been experimentally demonstrated¹ using a custom, in-house designed and built laser system². From the experimentally obtained CRBS spectra, macroscopic quantities such as the flow velocity, density and translational temperature can be extracted. CRBS has already been demonstrated to be the coherent analogue of spontaneous Rayleigh-Brillouin scattering and has been used for the in-situ measurement of nanoparticles in an arc discharge³.

Furthermore, we present progress made towards the utilization of the four wave mixing scheme for the characterization of electrons (in the form of coherent Thomson scattering⁴) and ions⁵. We show our theoretical study on how the charged species would behave in the presence of an intense, periodic electric field, and show simulated spectra under such conditions, as well as propose novel experimental techniques which could be utilized for the characterization of charged species in plasma.