Ballistic Focusing of Polyenergetic Protons Driven by Petawatt Laser Pulses
Ballistic Focusing of Polyenergetic Protons Driven by Petawatt Laser Pulses
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DOI：
10.1103/physrevlett.106.225003
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发表时间：
2011-06-02
影响因子：
8.6
通讯作者：
Zepf, M.
中科院分区：
文献类型：
--
作者：
Kar, S.;Markey, K.;Zepf, M.
通过使用具有350 μ m曲率半径的厚（250 μ m）靶，由拍瓦激光器驱动的强质子束被聚焦在距离靶近似1 mm的距离处，用于所有可检测的能量直到近似25 MeV。箔的厚度有利于束聚焦，因为它抑制了由在靶后侧处的峰值电子通量分布引起的束发散的动态演变。此外，由于目标厚度导致的固有光束发散度的减小放松了短程聚焦的曲率要求。能量分辨映射的质子束轨迹从网格射线照片推断的聚焦和数据同意一个简单的几何模型的基础上弹道束传播。
By using a thick (250 mu m) target with 350 mu m radius of curvature, the intense proton beam driven by a petawatt laser is focused at a distance of similar to 1 mm from the target for all detectable energies up to similar to 25 MeV. The thickness of the foil facilitates beam focusing as it suppresses the dynamic evolution of the beam divergence caused by peaked electron flux distribution at the target rear side. In addition, reduction in inherent beam divergence due to the target thickness relaxes the curvature requirement for short-range focusing. Energy resolved mapping of the proton beam trajectories from mesh radiographs infers the focusing and the data agree with a simple geometrical modeling based on ballistic beam propagation.