超短超强激光与固体靶相互作用所致X射线剂量实验研究

超短超强激光与固体靶相互作用可产生显著的X射线剂量，其辐射防护问题是辐射防护和激光等离子体物理的学科交叉问题，对超短超强激光装置安全运行至关重要。为验证清华大学所提出的剂量评估公式，对超短超强激光与固体靶作用所产生的X射线剂量开展了实验研究。设计了用于屏蔽靶室内超热电子和散射光子的屏蔽结构，仅测量超热电子和固体靶作用所产生的X射线剂量，并开展蒙特卡罗模拟评估其屏蔽效果。基于星光 Ⅲ激光装置对不同激光功率密度（7×1018~4×1019 W/cm2）下不同角度上的X射线剂量开展了实验测量，并与不同的剂量评估公式结果进行了比较分析，实验中还对不同剂量测量探测器的响应进行了比较。计算结果表明，所设计的屏蔽结构能很好地屏蔽超热电子和散射光子。实验结果表明，清华大学所提出的剂量评估公式较文献公式能更好地与实验结果吻合。随激光功率密度的增加，前向的X射线剂量较侧向增加得更快。

Experimental Study on Dose of X-ray Generated by Interaction between Ultra-short Ultra-intense Laser and Solid Target

The interaction between ultra-short ultra-intense laser and solid target could produce significant X-ray doses. The radiation protection problem is an interdisciplinary problem of radiation protection and laser plasma physics, which is essential for the safe operation of ultra-short ultra-intense laser device. In order to verify the dose calculation formula proposed by Tsinghua University, the X-ray dose generated by the interaction of ultra-short ultra-intense laser and solid target was studied through experiment. A shielding structure for shielding hot electron and scattered photon in the target chamber was designed so that only the X-ray dose generated by the interaction of hot electron and solid target was measured. The X-ray dose distribution at different angles was measured under different laser intensities (7×1018 4×1019 W/cm2) using XG-Ⅲ laser device. The measurement results were compared with the results from different dose evaluation formulas. The responses of different dose measurement detectors were also compared in this experiment. The experimental results show that the dose evaluation formula proposed by Tsinghua University is more consistent with the experiment results compared with the formula proposed in literature. With the laser intensity increase, the forward X-ray dose increases more rapidly than that in the lateral direction.