ELECTRON ACCELERATION IN PROPAGATING ELECTRON-PLASMA WAVES

Electrons of 2.3 MeV energy and light in the wavelength range from 2-lambda(0) to 1.28-lambda(0) scattered in the direction of incident laser have been observed from the plasmas of exploding thin foils created by a carbon dioxide laser. The correlation measurements of electrons and light, performed independently, pointed to a common physical origin for these near the quarter-critical density region of the plasma where low phase velocity plasma waves are driven. This also indicated that low-density forward Raman scattering with high phase velocity plasma waves may not be principally responsible for the energetic electrons. In order to interpret the experimental results a simple computer calculation has been performed obtaining the final energies of electrons trapped in freely propagating electron plasma waves with incrasing phase velocity.