Numerical Study of Change in Shape of Saturated Absorption Spectrum of Argon Arcjet Plasma by Strong Velocity-Changing Collisions

Saturated absorption (SA) spectra of argon arcjet plasma with the effect of strong velocity-changing collisions were numerically investigated. The spectrum was numerically reproduced by simulating the change of the velocity distribution interacting with the pump laser using the rate equation system representing two electronic states in the argon atoms. The SA spectra were classified into five types, which are composed of the linear combination of the Gaussian function, Lorentzian function, and inverted pedestals. We drew the maps of the types of the SA spectrum by varying the collision-induced velocity redistribution rate in the two electronic states and the decay rate among them. The possibility of the determination of the collisional parameters from the experiments was also discussed.