Proton beams from intense laser-solid interaction : effects of the target materials

Geng, Y. X. and Wu, D. and Yu, W. and Sheng, Z. M. and Fritzsche, S. and Liao, Q. and Wu, M. J. and Xu, X. H. and Li, D. Y. and Ma, W. J. and Lu, H. Y. and Zhao, Y. Y. and He, X. T. and Chen, J. E. and Lin, C. and Yan, X. Q. (2020) Proton beams from intense laser-solid interaction : effects of the target materials. Matter and Radiation at Extremes, 5 (6). 14854. ISSN 2468-2047 (https://doi.org/10.1063/5.0014854)

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Abstract

We report systematic studies of laser-driven proton beams produced with micrometer-thick solid targets made of aluminum and plastic, respectively. Distinct effects of the target materials are found on the total charge, cutoff energy, and beam spot of protons in the experiments, and these are described well by two-dimensional particle-in-cell simulations incorporating intrinsic material properties. It is found that with a laser intensity of 8 × 1019 W/cm2, target normal sheath acceleration is the dominant mechanism for both types of target. For a plastic target, the higher charge and cutoff energy of the protons are due to the greater energy coupling efficiencies from the intense laser beams, and the larger divergence angle of the protons is due to the deflection of hot electrons during transport in the targets. We also find that the energy loss of hot electrons in targets of different thickness has a significant effect on the proton cutoff energy. The consistent results obtained here further narrow the gap between simulations and experiments.