Studies of the two plasmon decay and stimulated Raman scattering instabilities in hot long scalelength plasmas. Final report

The experiments described in this paper were conducted on the GDL laser system at the University of Rochester's Laboratory for Laser Energetics. (1) During this period we conducted studies of Raman backscatter and two plasmon decay from thin foil targets irradiated by a high intensity 0.35 ..mu..m laser beam. The major conclusions of the work on thin foils are: (a) We have observed stimulated Raman back and side scattering, apparently below the convective Raman threshold for a linear density profile. (b) The scattered spectrum shows a splitting around w/sub 0//2 which is not fully understood, but it is most probably caused by mode conversion of the plasma waves from 2w/sub p/ decay into electromagnetic waves. (c) High-energy electrons were observed from plasmas with densities below n/sub c/. The generation mechanism seems to be more efficient at n/sub c/4.