Effect of laser ripple on the beat wave excitation and particle acceleration

This paper presents the effect of ripple on the plasma wave excitation process and acceleration of electrons in a laser produced plasma. The plasma wave is generated by the beating of two coaxial lasers of frequencies ω₁ and ω₂, such that ω₁- ω₂ ≅ ω_p. One of the main laser beams also has intensity spikes. The nonlinearity due to the relativistic mass variation depends not only on the intensity of one laser beam but also on the second laser beam. Therefore the behavior of the first laser beam affects the second laser beam, hence cross-focusing takes place. Owing to the interaction of ripple and the main laser beams, the ripple grows inside the plasma. The behavior of the ripple in the plasma affects the excitation of the electron plasma wave as well as the electron acceleration. The amplitude of the electron plasma wave and the electron energy are calculated, in the presence of ripple.