Autoresonant excitation of space-time quasicrystals in plasma
Autoresonant excitation of space-time quasicrystals in plasma
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DOI：
10.1103/physrevresearch.4.023150
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发表时间：
2022-01
影响因子：
4.2
通讯作者：
V. Munirov;L. Friedland;J. Wurtele
中科院分区：
文献类型：
--
作者：
V. Munirov;L. Friedland;J. Wurtele
我们从理论上和数值上证明了等离子体的热流体模型支持时空准晶体结构。这些结构是高度非线性的两相离子声波，当等离子体被两个小幅度啁啾频率的有源驱动时，它们会被自共振激发。这些波表现出的密度偏移实质上超过了平衡等离子体密度。值得注意的是，即使关闭小振幅驱动器，这些极端非线性的波仍然存在。将惠瑟姆平均变分原理应用于流体方程的拉格朗日公式，导出了弱非线性解析理论。所得到的耦合弱非线性方程组与热流体模型的完全非线性模拟结果很好地吻合。推导了自共振激发所需的解析条件和阈值，并与仿真结果进行了比较。弱非线性理论指导和指导了两相准晶结构在一个驱动低于阈值时如何“融化”成单相行波的数值研究。这些非线性结构可能应用于极强激光脉冲的等离子体光子学，这些激光脉冲受到线性波密度扰动较小的限制。
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.