Experiments on the mixing of electromagnetic waves in a plasma

Enhanced electron-density fluctuations in a plasma jet are produced by the nonlinear interaction of the plasma with two pulsed dye-laser beams, one of which is of variable frequency. The properties of the enhanced fluctuations are studied as a function of the laser intensities and frequencies by observing the spectra of ruby-laser radiation scattered by the density fluctuations. The ruby laser also pumps the dye lasers. The dependence of the scattered signals on the laser intensities is well described by theory, but the response of the plasma to mixing forces of variable frequency is anomalous