Intra-pulse transition between ion acceleration mechanisms in intense laser-foil interactions
Intra-pulse transition between ion acceleration mechanisms in intense laser-foil interactions
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DOI：
10.1063/1.4954654
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发表时间：
2016-06-01
影响因子：
2.2
通讯作者：
McKenna, P.
中科院分区：
文献类型：
--
作者：
Padda, H.;King, M.;McKenna, P.
当用强激光脉冲照射金属箔时，可以发生多种离子加速机制，其中主导机制在相互作用的过程中发生变化。测量高能质子束的空间强度分布被用来研究从辐射压力加速到能量驱动过程的转变。数值结果表明，辐射压力驱动激光焦斑的空间范围内的目标离子的膨胀增加，这引起相对低能量的鞘加速质子的径向偏转，以形成环形分布。通过目标箔厚度的变化，环的开度角被示出为与在相互作用期间发生的时间透明度的点相关，并且当其发生在激光强度分布的峰值处时被最大化。相应的实验测量的环的尺寸变化与目标厚度表现出相同的趋势，并提供洞察脉冲内的激光等离子体演化。出版社：AIP Publishing
Multiple ion acceleration mechanisms can occur when an ultrathin foil is irradiated with an intense laser pulse, with the dominant mechanism changing over the course of the interaction. Measurement of the spatial-intensity distribution of the beam of energetic protons is used to investigate the transition from radiation pressure acceleration to transparency-driven processes. It is shown numerically that radiation pressure drives an increased expansion of the target ions within the spatial extent of the laser focal spot, which induces a radial deflection of relatively low energy sheath-accelerated protons to form an annular distribution. Through variation of the target foil thickness, the opening angle of the ring is shown to be correlated to the point in time transparency occurs during the interaction and is maximized when it occurs at the peak of the laser intensity profile. Corresponding experimental measurements of the ring size variation with target thickness exhibit the same trends and provide insight into the intra-pulse laser-plasma evolution. Published by AIP Publishing.