长脉冲keV X射线源的辐射特征

胡广月; 刘慎业; 张继彦; 杨家敏; 丁永坤; 胡昕; 黄翼祥; 杜华冰; 易容清; 郑坚

长脉冲keV X射线源的辐射特征

1.
中国科学院基础等离子体物理重点实验室, 合肥 230026;
2.
中国科学技术大学近代物理系, 合肥 230026;
3.
中国工程物理研究院激光聚变研究中心, 四川绵阳 621 900

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出版历程
- 刊出日期: 2007-05-15

Emission characteristic of long laser pulse keV X-ray source

1.
Key Laboratory of Basic Plasma Physics,Chinese Academy of Scinese,Hefei 230026,China;
2.
Department of Modern Physics,University of Science and Technology of China,Hefei 230026,China;
3.
Research Center of Laser Fusion,CAEP,P.O.Box 919-986,Mianyang 621900,China

摘要

摘要: 利用神光Ⅱ第九路2 ns长脉冲激光束作用厚钛固体靶，研究了产生的keV X射线源的辐射区域和总辐射功率的时间行为。结果表明：在长脉冲激光作用厚固体靶时，硬X射线线辐射功率的时间行为以及辐射体积的时间行为与激光脉冲波形一致；长脉冲时，等离子体2维膨胀效应非常显著，keV X射线线辐射的径向辐射区域在激光焦斑尺寸附近达到饱和，导致X射线线辐射功率出现饱和，且keV X射线线辐射的辐射体积正比于焦斑尺寸的3次方。从理论和实验角度研究了在同样入射激光能量下，辐射功率随激光焦斑尺寸的变化关系，发现keV X射线线辐射的饱和辐射功率正比于焦斑尺寸的5/3次方，理论结果与实验结果一致。并讨论了相同基频输出激光能量下，keV X射线辐射总功率随激光波长的变化关系，发现即使考虑了倍频效率的影响，短波长激光仍然有利于keV X射线的发射。
- X射线源 /
- 长脉冲 /
- 2维膨胀效应 /
- 辐射区域 /
- 焦斑尺寸 /
- 激光波长
Abstract: Multi-keV X-ray sources generated by irradiating thick solid target with a 2 ns-duration laser pulse are investigated on Shenguang Ⅱ laser facility. With the long laser pulse, the significant three-dimensional expansion of the plasma leads to that the longitudinal scale length of the X-ray emission region is finally determined by the laser spot size and the emission volume is proportional to the third power of the laser spot size. Theoretical analysis shows that X-ray flux can be enhanced by increasing the laser spot size because in the steady state the X-ray flux is proportional to the five-third power of the laser sopt size under the same laser power. The scaling law is in good agreement with the experimental data. It is also shown that short wavelength laser is suitable for the multi-k
- x-ray source /
- long laser pulse /
- three dimension expansion /
- emission region /
- laser spot size /
- laser wavelength