Electron bunch dynamics and emission in particle-in-cell simulations of relativistic laser–solid interactions: On density artifacts, collisions, and numerical dispersion
Electron bunch dynamics and emission in particle-in-cell simulations of relativistic laser–solid interactions: On density artifacts, collisions, and numerical dispersion
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DOI：
10.1063/5.0140028
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发表时间：
2023-06
影响因子：
2.2
通讯作者：
N. Fasano;M. R. Edwards;J. Mikhailova
中科院分区：
文献类型：
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作者：
N. Fasano;M. R. Edwards;J. Mikhailova
相对论强度激光-固体相互作用中致密电子束的亚光循环动力学导致高次谐波和阿秒光脉冲的发射。细胞内粒子模拟准确模拟这些动力学的能力对于预测发射特性至关重要，因为阿秒脉冲强度取决于发射时的电子密度分布以及发射电子束中单个电子洛伦兹因子的时间分布。在这里，我们表明在一维无碰撞模拟中，发射电子束的峰值密度随着模拟网格空间分辨率的增加而增加。当碰撞添加到模型中时，峰值电子密度变得与空间分辨率无关。研究表明，碰撞会增加发射电子的洛伦兹因子的峰值随时间的扩展，尤其是在远离最佳生成条件的情况下，从而导致与无碰撞模拟中获得的阿秒脉冲强度相比较低。
Sub-optical-cycle dynamics of dense electron bunches in relativistic-intensity laser–solid interactions lead to the emission of high-order harmonics and attosecond light pulses. The capacity of particle-in-cell simulations to accurately model these dynamics is essential for the prediction of emission properties because the attosecond pulse intensity depends on the electron density distribution at the time of emission and on the temporal distribution of individual electron Lorentz-factors in an emitting electron bunch. Here, we show that in one-dimensional collisionless simulations, the peak density of the emitting electron bunch increases with the increase in the spatial resolution of the simulation grid. When collisions are added to the model, the peak electron density becomes independent of the spatial resolution. Collisions are shown to increase the spread of the peaks of Lorentz-factors of emitting electrons in time, especially in the regimes far from optimum generation conditions, thus leading to lower intensities of attosecond pulses as compared to those obtained in collisionless simulations.