Autoresonant excitation of space-time quasicrystals in plasma

TL;DR

This paper demonstrates that a warm plasma supports highly nonlinear space-time quasicrystalline structures excited via autoresonance, with analytical theory aligning well with numerical simulations, revealing thresholds and stability conditions.

Contribution

The paper introduces a novel theoretical and numerical analysis of autoresonant excitation of space-time quasicrystals in plasma, including analytical thresholds and nonlinear wave behavior.

Findings

Space-time quasicrystals are supported in warm plasma models.

Autoresonant excitation leads to density excursions exceeding equilibrium.

Nonlinear structures persist even after drives are turned off.

Abstract

We demonstrate theoretically and numerically that a warm fluid model of a plasma supports space-time quasicrystalline structures. These structures are highly nonlinear, two-phase, ion acoustic waves that are excited autoresonantly when the plasma is driven by two small amplitude chirped-frequency ponderomotive drives. The waves exhibit density excursions that substantially exceed the equilibrium plasma density. Remarkably, these extremely nonlinear waves persist even when the small amplitude drives are turned off. We derive the weakly nonlinear analytical theory by applying Whitham's averaged variational principle to the Lagrangian formulation of the fluid equations. The resulting system of coupled weakly nonlinear equations is shown to be in good agreement with fully nonlinear simulations of the warm fluid model. The analytical conditions and thresholds required for autoresonant excitation to occur are derived and compared to simulations. The weakly nonlinear theory guides and informs numerical study of how the two-phase quasicrystalline structure "melts" into a single phase traveling wave when one drive is below a threshold. These nonlinear structures may have applications to plasma photonics for extremely intense laser pulses, which are limited by the smallness of density perturbations of linear waves.