Abstract:
A study is made of two-photon resonant scattering by oscillations of excited ions in a low-temperature plasma. It is shown that an alternating electric field of frequency ω0 accelerating these ions produces not only the usual nonlinear interference structures in the laser radiation spectra, but also–because of a parametric resonance–satellite lines at the Raman frequencies ωμ =ω ±ω0 (ωμ and ω are the frequencies of laser fields). This phenomenon is used in the proposed laser spectroscopy method for detecting natural and forced oscillations of a low-temperature plasma due to high-frequency modulation of the voltage maintaining the gas discharge. Nonlinear parametric resonances corresponding to ion-acoustic and other instabilities may be used in plasma diagnostics.