We study the setting up of relativistic ponderomotive non-linearity in an under-dense collisionless cold plasma. Using the fluid model, coupled system of equations of the laser beam and electron plasma oscillations has been derived. We present the numerical simulation for this coupled system of equations, when the coupling arises through relativistic ponderomotive non-linearity. The filamentation of the laser beam has been found to vary appreciably with perturbation wave number. The results show that with time, localized structures become more complex and the plasma oscillation frequency spectra have several harmonic peaks at terahertz frequencies when the electron plasma frequency is in terahertz range and laser frequency is around 2.35 × 10 15 rad/s. We also present the semi-analytical model to capture the underlying physics.

中文翻译：

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无碰撞等离子体中超短激光脉冲的相对论质动力非线性和成丝的瞬态设置

我们研究了低密度无碰撞冷等离子体中相对论质动力非线性的建立。利用流体模型，推导出了激光束和电子等离子体振荡的耦合方程组。当耦合通过相对论质动力非线性产生时，我们给出了这个耦合方程组的数值模拟。已经发现激光束的成丝随扰动波数而明显变化。结果表明，随着时间的推移，当电子等离子体频率在太赫兹范围内，激光频率在2.35×10 15 rad/s左右时，局域结构变得更加复杂，并且等离子体振荡频谱在太赫兹频率处具有多个谐波峰。我们还提出了半解析模型来捕捉基础物理。