Stimulated Raman scattering, two-plasmon decay, and hot electron generation from underdense plasmas at 0.35 μm

Abstract

Experimental studies of stimulated Raman back and side scattering, two-plasmon decay, and the generation of high-energy electrons in 0.35 μm laser plasma interaction are presented. To isolate the various phenomena occurring at different densities, we have attempted to control the maximum plasma density by varying the thickness of the foil targets. The scattered light frequency is used as a diagnostic to measure the peak plasma density. Time integrated and time resolved scattered spectra for variable plasma densities are discussed. Effects of self-generated magnetic fields and plasma temperature on SRS and 2ωp decay, respectively, are examined as possible mechanisms responsible for splitting of the backscattered spectrum at ω0/2. A discussion of the effects of a parabolic density profile on the SRS threshold is also included. Finally, the measured energy and angular distribution of the high-energy electrons are discussed. Two-plasmon decay is suggested as the probable mechanism generating the hot electrons.