Theoretical investigation into effect of laser focal spot size on extreme ultraviolet radiation

Lan Xiang; Li Xuecheng; Yang Shunyi; Tang Huibo; Kuang Longyu; Hu Guangyue

doi:10.11884/HPLPB202537.240327

Volume 37 Issue 5

Mar. 2025

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Lan Xiang, Li Xuecheng, Yang Shunyi, et al. Theoretical investigation into effect of laser focal spot size on extreme ultraviolet radiation[J]. High Power Laser and Particle Beams, 2025, 37: 052003. doi: 10.11884/HPLPB202537.240327

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Lan Xiang, Li Xuecheng, Yang Shunyi, et al. Theoretical investigation into effect of laser focal spot size on extreme ultraviolet radiation[J]. High Power Laser and Particle Beams, 2025, 37: 052003. doi: 10.11884/HPLPB202537.240327

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Theoretical investigation into effect of laser focal spot size on extreme ultraviolet radiation

doi: 10.11884/HPLPB202537.240327

Lan Xiang^1
,,
Li Xuecheng²,
Yang Shunyi¹,
Tang Huibo^{1
,
,},
Kuang Longyu^{2
,
,},
Hu Guangyue^{1, 3
,
,}

1.
Key Laboratory of Geospace Environment of Chinese Academy of Sciences, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China
2.
Laser Fusion Research Center, CAEP, Mianyang 621900, China
3.
Center for Excellence in Ultra-intense Laser Science (CEULS), Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 200031, China

Received Date: 2024-09-14
Accepted Date: 2024-11-29
Rev Recd Date: 2024-11-27

Available Online: 2025-02-15

Publish Date: 2025-03-31

Abstract

Abstract

To understand the effect of laser focal spot size on the extreme ultraviolet conversion efficiency and the physical mechanism that produces the effect, we developed a two-dimensional transient expansion model of laser ablation of planar target to produce coronal plasma by means of theoretical analysis. It is found that under condition with light intensity of 7.45×10¹⁰ W/cm², full width at half maxima of 5 ns, wavelength of 1064 nm, as the laser focal spot radius increases from 60 μm to 300 μm, the corresponding extreme ultraviolet conversion efficiency increases from 1% to 5.5%, while the corresponding extreme ultraviolet conversion efficiency stays at 5.5% after the focal spot radius is larger than 300 μm. This is due to the fact that the plasma in the coronal region generated by laser ablation of planar targets expands from the initial one-dimensional expansion to the subsequent two-dimensional expansion, which determines the saturation size of the plasma region emitting extreme ultraviolet light and ultimately determines the conversion efficiency of the extreme ultraviolet light. Our theoretical analysis on trend of conversion efficiency with focal spot radius can explain the physical phenomena observed in the laser ablation of a tin target experiment.
- laser produced plasma,
- extreme ultraviolet radiation,
- laser focal spot size,
- theoretical analysis,
- two-dimensional expansion

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References(26)

References

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