量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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To generate bright water-window (WW) soft x rays (2.3–4.4 nm), gold slab targets were irradiated with laser pulses (1064 nm, 7 ns, 1 J). Emission spectroscopy showed that the introduction of low-pressure nitrogen enhanced the soft x-ray yield emitted from the laser-produced Au plasma. The intensity of the WW x-ray transported in a 400-Pa N2 atmosphere from the laser-produced plasma increased by 3.8 times over that in vacuum. Considering a strong x-ray absorption, the x-ray yield emitted directly from the Au plasma in the N2 gas was evaluated to be 13 times higher than that in vacuum. Although similar measurements were made for various gases, only N2 gas causes an increase in a soft x-ray yield. The processes leading to this enhancement mechanism were revealed by using hydrodynamic simulation and atomic structure codes.
Enhancement of water-window soft x-ray emission from laser-produced Au plasma under low-pressure nitrogen atmosphere
