Thermal Plasma Diagnostics Using Tunable Dye Laser (Report I) : Resonance Fluorescence in a High Power Microwave Discharge(Welding Physics, Process & Instrument)

Laser-induced fluorescence method (LIFM) was applied to a nearly thermal high density plasma (n_e=10^<13>-10^<15>cm^<-3>) of hygrogen gas. Resonance scattering was measured on the H_α line and the saturation curves of the fluorescence were obtained for various electron densities. The power broadening of the scattered signal was clearly observed at fully saturated conditions. From the analysis of this phenomenon, it was possible to select out the contribution of the homogeneous broadening such as Stark one in the emission spectrum without laser pumping, even when the spectrum was governed by the Doppler (inhomogeneous) broadening.