2026-10-19 核融合科学研究所,大阪大学,京都大学,高輝度光科学研究センター,量子科学技術研究開発機構
図１. 高強度フェムト秒レーザーによる微細ロッド集合体ターゲットのプラズマ化ダイナミクスに対するX線自由電子レーザーを用いた観測実験の概念図。
＜関連情報＞
- https://www.nifs.ac.jp/news/research/261019.html?utm_source=chatgpt.com
- https://www.nature.com/articles/s42005-026-02872-5
高エネルギー密度プラズマのマルチスケール構造測定のためのビームストップ不要の小角X線散乱 Beamstop-free small-angle X-ray scattering for multiscale structure measurement of high-energy-density plasma
Masato Ota, Ryutaro Matsui, Melanie Rodel, Shunsuke Egashira, Tomohiro Izumi, Yoshiharu Nakagawa, Yushiro Matsumoto, Otono Kuramoto, Hiroki Ishiara, Kosuke Maeda, Tatiana Pikuz, Alexander Pirozhkov, Alejandro Laso Garcia, Lingen Huang, Alessio Morace, Takumi Minami, Kentaro Sakai, Yuji Fukuyama, Yuto Maeda, Kohei Endo, Soma Nitta, Genki Kamimura, Tomoya Taguchi, Yuki Abe, … Youichi Sakawa
Communications Physics Published:16 October 2026
DOI:https://doi.org/10.1038/s42005-026-02872-5
Abstract
The advent of free-electron lasers has enabled in-situ small-angle X-ray scattering (SAXS) measurements of laser-produced high-energy-density plasma at solid density, with nanometer- and femtosecond-scale resolution. Such plasmas generally exhibit gentle density gradients, which suppress large-angle scattering signals while small-angle scattering components dominate near the direct X-ray beam; the latter signals were hard to access in the conventional SAXS method due to the use of a beamstop. Here, we demonstrate a beamstop-free SAXS system comprising layered metallic filters for optimal attenuation of diffraction signals. It enables continuous acquisition of wide q-range/angular scattering signals with a large dynamic range, including the critical small-angle region containing the direct X-ray beam. This method was applied to a two-dimensional array of submicron columnar plasmas generated by irradiating a high-intensity laser pulse onto an assembly of high-aspect-ratio silicon rods with well-defined sharp edges. We experimentally resolve the microscale and macroscale rarefaction dynamics of bulk electrons driven by the pump-laser pre-pulse and main pulse, revealing the initial plasma scale length as a key parameter governing laser absorption in structured targets. Beamstop-free SAXS enables single-shot multiscale structure measurement and establishes a route toward exploration of stochastic plasma dynamics under high-energy-density conditions, including filamentation instability and turbulence.
