Dynamics of harmonic generation in a laser plasma

The results of a dynamic theory of the effect of intense eletromagnetic radiation on a plasma are reported. These results can be used as the basis for an experimental study of the nonlinear state of a plasma in which one would measure the time evolution of the coefficients for conversion into the higher harmonics and that of the relative intensity of the emission from the plasma at the second and third harmonics. At the transition from subsonic to supersonic plasma flow, the decrease in the internal plasma field causes both a decrease in the absolute values of the conversion coefficients and a relative decrease in the efficiency of the third-harmonic generation, K3/K2. This analysis indicates that it is possible to obtain information on the characteristic dimension for the changes in the plasma density from the relative intensities of the second and third harmonics