The Study of Photon Acceleration Driven by the Near-forward Scattering in the Intense Laser Under-dense Plasma Interaction

The mechanism of photon acceleration driven by the near-forward scattering (NFS) in interaction between an intense laser and under-dense plasmas is studied particle-in-cell (PIC) simulation. This utilizes tunneling ionization effect to stimulate electron plasma waves when pulse propagates plasmas. density inhomogeneous both longitudinal transverse direction. In direction, a steep ionized front generated incident ionizing helium gas. Around front, interacts with waves, thus generating first kind NFS waves. Compared frequency laser, wave increases. characteristic peak spectrum. have different phase velocities, which makes undergo process upshift its frequency. second Owing fact that inhomogeneity much larger than perturbation wave, model dispersion relationships, are based on theory like stimulated Raman scattering, no longer applicable this case. Our further study shows still satisfy energy conservation momentum is, they three-wave coupling relationship under condition heterogeneous density, explaining appearance two peaks spectrum their growth wave-vector space. has significant reference evolution plasma.