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在中国科学院物理研究所“极光Ⅱ号”飞秒激光装置上,对激光与薄膜靶相互作用产生的靶后质子束特性进行了实验研究.结果发现,在主脉冲前存在较强的飞秒预脉冲的情况下,通过适当地对激光束散焦,可以使质子束的转换效率提高3个数量级,并同时改善质子束的准直性.分析表明,激光散焦的方法可以有效地抑制预脉冲的流体力学效应对质子加速的负面影响,从而提高质子的转换效率.此外,粒子模拟还发现,散焦量增大时可以产生更多的中低能超热电子,这也有利于建立高质量的质子加速电场.
The proton beam characteristics of the target produced by the interaction between the laser and the thin film target were studied experimentally at the Institute of Physics, Chinese Academy of Sciences under the “Aurora II” femtosecond laser device. The results showed that there was a strong fly-by before the main pulse Sec pre-pulse, by appropriately defocusing the laser beam, the conversion efficiency of the proton beam can be improved by three orders of magnitude and the collimation of the proton beam can be improved at the same time. The analysis shows that the laser defocusing method can effectively restrain In addition, the particle simulation also found that increasing the defocus amount can produce more moderate-low-energy hyperthermal electrons, which is also beneficial to the establishment of high The mass proton accelerating electric field.