Temperature fields in glow discharges measured with ultra violet filtered Rayleigh scattering

Summary form only given, as follows. We report filtered Rayleigh scattering temperature measurements in weakly ionized plasmas. A measurement system that pairs the frequency tripled output (254 nm) of a titanium sapphire laser with a narrow linewidth atomic mercury filter was used. The Rayleigh scattering signal was used to infer the gas temperature, while the atomic mercury filter served to suppress spurious background. To demonstrate the technique we performed point measurements using a photomultiplier tube as the detector. By shifting the position of the discharge tube in this configuration, we obtained 1-D temperature profiles in diffuse 50 torr glow discharges of argon, argon mixed with 1% nitrogen, and nitrogen. These measurements were consistent with our calculations. The filtered Rayleigh Scattering method is particularly useful for studying contracted (filamentary) discharges, since their lack of symmetry makes it challenging to measure them by other means. Using an intensified camera as the detector we obtained 2-D temperature fields in a 50 torr argon discharge in both a diffuse mode (20 mA) and a contracted mode (70-130 mA). By comparing the contracted temperature profiles to calculations: it is possible to infer the width of the current distribution in the contracted plasmas.