Numerical simulations were used to investigate the electron bunching induced by a laser pulse in its penetration into a plasma that has a nonuniform density profile at the vacuum – plasma boundary, which reaches a plateau. A mechanism was found to exist for this plasma which fosters a denser electron grouping in the generated bunch in comparison with the plasma with a sharp boundary. This mechanism is related to the nonstationarity of the wake wave produced by the laser pulse at the beginning of the plasma density plateau.

中文翻译：

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穿过非均匀等离子体边界时超相对论性强激光脉冲引起的电子聚集机制

数值模拟用于研究激光脉冲穿透进入等离子体时所产生的电子束，该等离子体在真空-等离子体边界处达到一个不稳定的密度分布。已发现该等离子体存在一种机制，与具有尖锐边界的等离子体相比，该机制可在生成的束中促进更密集的电子分组。该机制与等离子体密度平稳期开始时激光脉冲产生的尾波的非平稳性有关。