Diagnostics of neutral particles in a low pressure DC glow discharge using single shot coherent Rayleigh-Brillouin scattering*

Single shot coherent Rayleigh-Brillouin scattering (CRBS), a non-linear, four-wave mixing laser diagnostic technique, is applied to measure the translational temperature and density of neutral species in a low pressure, xenon, DC glow discharge. The single shot CRBS configuration scans the entire velocity distribution function of the neutral species in the medium in the duration of a single laser shot (approximately 150 ns), allowing for rapid spectral acquisition. To enable a stronger signal at low pressures (here ~15 Torr), the system used employs a dual color configuration with the pump beams operating at 1064 nm and the probe beam at 532 nm; all three beams having the same pulse duration. CRBS spectra of neutral species are obtained radially across the xenon glow discharge, mapping horizontal temperature and density profiles. Experimentally obtained spectral lineshapes show good agreement when compared to simulated ones. Single shot CRBS exhibits the significant advantages of being able to measure at both low densities and optically noisy environments. The CRBS measurements within a glow discharge presented here can lead to diagnostics of neutral species in similar environments such as arc discharges, flames, plasma torches, etc.