Four-wave mixing diagnostics for neutrals, ions and electrons in low (and high) temperature plasmas*

Single shot, non-resonant, laser-based four-wave mixing (FWM) diagnostics pave a novel way to characterize the flow proprerties (temperature, density, flow velocity vector) of neutral and ionized gases, with great spatio-temporal resolution and increased signal-to-noise-ratio (SNR) owing to their coherent nature. Here, we present the results and working progress towards using single-shot coherent Rayleigh-Brillouin scattering (CRBS) for the radial and axial measurement of the velocity distribution function (VDF) of neutrals in a glow discharge [1], [2], prior to its further utilization in arc discharges. In addition, we demonstrate the utilization of a similar FWM chirping concept for the development of a novel coherent Thomson scattering scheme [3]. Furthermore, we discuss and demonstrate the applicability of single shot CRBS for the quantitative determination of ultrafast ionization and thermalization in nanosecond repetitively pulsed discharges (NRPs). Additionally, we demonstrate our progress in performing coherent diagnostics on driven Langmuir waves to reveal electronic temperature and density in a plasma[4]. Finally, we demonstrate the utilization of single shot CRBS for the fundamental and detailed understanding of nanoparticle synthesis by plasma.