Formation of electromagnetic postsolitons in plasmas

With particle-in-cell simulations we show that electromagnetic relativistically strong solitons, formed in the wake of the laser pulse during the interaction of a high-intensity ultrashort laser pulse with a collisionless plasma, evolve asymptotically into postsolitons. A postsoliton is a slowly expanding cavity in the ion and electron densities which traps electromagnetic energy. Fast ions are accelerated during the postsoliton formation. Postsolitons are elementary components of the relativistic electromagnetic turbulence in laser-irradiated plasmas.