Spot size dependence of laser accelerated protons in thin multi-ion foils
Spot size dependence of laser accelerated protons in thin multi-ion foils
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DOI：
10.1063/1.4882436
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发表时间：
2014-06-01
影响因子：
2.2
通讯作者：
Chen, Shih-Hung
中科院分区：
文献类型：
--
作者：
Liu, Tung-Chang;Shao, Xi;Chen, Shih-Hung
本文用数值计算方法研究了用碳氢薄膜加速准单能质子时，圆偏振激光束的光斑大小对质子能量的影响。所使用的质子加速方案是激光辐射压力和由于碳离子的屏蔽库仑排斥的组合。我们观察到，斑点的大小起着至关重要的作用，在确定电子屏蔽的碳离子箔的净电荷，从而质子加速的效率。利用具有固定输入能量和脉冲长度的激光脉冲撞击碳-氢箔，具有较小光斑尺寸的激光束可以产生较高能量但较少的准单能质子。我们研究了质子能量与激光光斑尺寸的关系，得到了最大质子能量通量的最佳光斑尺寸。在最佳光斑尺寸下，用功率为250 TW、能量为10 J的激光束和厚度为0.15波长、临界密度为49的90%碳和10%氢靶，可以产生80 MeV的包含10（8）个以上质子的准单能质子束。(C)2014 AIP出版有限责任公司。
We present a numerical study of the effect of the laser spot size of a circularly polarized laser beam on the energy of quasi-monoenergetic protons in laser proton acceleration using a thin carbon-hydrogen foil. The used proton acceleration scheme is a combination of laser radiation pressure and shielded Coulomb repulsion due to the carbon ions. We observe that the spot size plays a crucial role in determining the net charge of the electron-shielded carbon ion foil and consequently the efficiency of proton acceleration. Using a laser pulse with fixed input energy and pulse length impinging on a carbon-hydrogen foil, a laser beam with smaller spot sizes can generate higher energy but fewer quasi-monoenergetic protons. We studied the scaling of the proton energy with respect to the laser spot size and obtained an optimal spot size for maximum proton energy flux. Using the optimal spot size, we can generate an 80MeV quasi-monoenergetic proton beam containing more than 10(8) protons using a laser beam with power 250TW and energy 10 J and a target of thickness 0.15 wavelength and 49 critical density made of 90% carbon and 10% hydrogen. (C) 2014 AIP Publishing LLC.