Lateral confinement of fast electrons and its impact on laser ion acceleration
Lateral confinement of fast electrons and its impact on laser ion acceleration
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DOI：
10.1103/physrevresearch.3.023193
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发表时间：
2021-06-09
影响因子：
4.2
通讯作者：
Sentoku, Y.
中科院分区：
文献类型：
--
作者：
Iwata, N.;Kemp, A. J.;Sentoku, Y.
在强烈的激光-等离子体相互作用中，最大化激光光斑区域中快电子的密度是实现等离子体加热和粒子加速的关键。我们发现，当激光光斑尺寸与目标箔厚度相比较大时，由于光斑区域内等离子体表面波动场的散射，箔中循环的快速电子在横向上表现出“随机游走”。我们将横向运动建模为扩散，并发现由此产生的扩散速度比弹道传输的速度慢得多。因此，快电子在斑点区域积聚，随着时间的推移，它们的密度通常会比激光加速的快电子密度大 10 倍。靶中快速电子密度的增强将离子加速推向更有效的状态。
In intense laser-plasma interactions, maximizing the density of fast electrons in the laser spot area is key to achieving plasma heating and particle acceleration. We find that when the laser spot size is large compared with the target foil thickness, fast electrons circulating in the foil show a "random walk" in the lateral direction due to the scattering by fluctuating fields at the plasma surface inside the spot area. We model the lateral motion as a diffusion, and find the resulting diffusion velocity is much slower than the speed of the ballistic transport. Hence, fast electrons accumulate in the spot region, and over time their density becomes typically 10 times greater than the laser-accelerated fast electron density. The enhancement of fast electron density in the target pushes the ion acceleration to more efficient regime.