Model study on laser interaction with near-critical density plasma

The formation and evolution of laser-induced post-solitons in near-critical density plasma are studied using the two-dimensional theoretical model and particle in cell simulation. The study shows that a considerable part of laser energy can penetrate plasma, which is then trapped in an empty cavity bounded by overdense plasma peaks. The self-trapped electromagnetic fields remain as a half-cycle standing wave. The amplitude of these electromagnetic fields peaks at the cavity center and vanishes at the boundary. As the cavity expands slowly, the field amplitude decreases, and the oscillation frequency is reduced to merely a small faction of laser frequency.