Laser-plasma diagnostics in the critical-density region using the method of Raman scattering

Raman scattering of probing light was used for the first time to investigate a plasma in the region of critical density = 10 to the 21st/cu cm for neodymium-laser heating radiation. The appearance of radiation in the scattering spectrum, which is frequency-shifted relative to the probing wave by an amount equal to the electron Langmuir frequency for the critical density region, indicates that the intensity of plasma oscillations increases sharply in this region. The nonlinear processes that occur in the plasma in the critical density region are identified on the basis of an analysis of the scattering spectrum of the probing light.