Space-time quasicrystals in plasma

We demonstrate that warm fluid equations of plasma support multiphase solutions for ion acoustic and electron plasma waves. These highly nonlinear waves are excited by using autoresonance -- a phenomenon in which the waves automatically adjust their amplitudes to stay phase-locked with chirped-frequency ponderomotive external drives. The multiphase waves form spatiotemporal quasicrystalline structures that persist even after we stop driving. Due to the threshold nature of autoresonance, such quasicrystals can suddenly "melt" or "crystallize" when the critical condition is being passed. The possible utility of these coherent structures for particle acceleration and plasma photonics experiments is being investigated. We conduct fully nonlinear numerical simulations as well as develop an analytical weakly nonlinear theory based on application of Whitham's averaged Lagrangian method. The analytical theory allows one to estimate and choose the laser parameters required for autoresonant excitation of multiphase waves in plasma.