Single-shot, non-resonant, four-wave mixing laser diagnostics for low temperature plasmas.*

Single-shot coherent Rayleigh-Brillouin scattering (CRBS) is experimentally demonstrated for the measurement of the velocity distribution function (VDF) of neutral species in a glow discharge, from which macroscopic quantities, such as the flow velocity, density, and translational temperature, can be extracted. In CRBS, a four-wave mixing technique, the resulting single shot (~200 ns) CRBS lineshape is a direct mapping of the medium's VDF. CRBS has already been demonstrated to be the coherent analogue of spontaneous Rayleigh-Brillouin scattering and for measurement of nanoparticles in an arc discharge¹. In this study, single-shot CRBS is applied to measure simultaneously the temperature and density of neutral species in a weakly ionized DC glow discharge plasma (xenon gas, 15 Torr). For this application, we employ a newly developed dual-color CRBS scheme^2,3 .

The temperature and density of neutral xenon particles inside the DC glow discharge is evaluated simultaneously by analyzing the resolved single-shot CRBS lineshapes and is characterized as a function of the discharge current and radial position, successfully demonstrating the use of CRBS in a partially ionized plasma environment. A fluid model of the glow discharge is also developed and there is good agreement between the simulation and the experimental measurements in the glow discharge.

1) 10.1103/PhysRevApplied.9.014031

2) 10.1088/1361-6463/acb275

3) 10.1364/OE.470764