Stimulated Raman cascade and photon condensation in intense laser plasma interaction

Abstract

Stimulated Raman scattering, stimulated Raman cascade, and the transition from Raman cascade into photon condensation, induced by linearly polarized intense laser interacting with an underdense uniform collisionless plasma, are studied by particle simulations. In addition to the stimulated Raman scattering process, the simulation results can reveal a clear physics picture on stimulated Raman cascade and cascade-into-condensation. It is found that, at appropriate laser amplitude and plasma conditions, a large amplitude relativistic electromagnetic soliton forms due to the strong photon condensation. The electromagnetic frequency of the soliton is about half of the unperturbed electron plasma frequency. The transverse electric field, magnetic field, and electrostatic field inside a soliton region have half-, one-, and one-cycle structure in space, respectively. Finally, the influence of the electron temperature and the ion dynamics are discussed briefly.