K壳层X射线光谱：惯性约束聚变中受激拉曼散射的可靠探针
X-Ray Spectroscopy for Characterizing Stimulated Raman Scattering in Inertial Confinement Fusion
- Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University（四川大学核科学技术学院辐射物理与技术教育部重点实验室）
- National Key Laboratory of Plasma Physics, Laser Fusion Research Center, China Academy of Engineering Physics（中国工程物理研究院激光聚变研究中心等离子体物理全国重点实验室）
- College of Intelligent Manufacturing, Sichuan University of Arts and Science（四川文理学院智能制造学院）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
本研究利用非局域热力学平衡碰撞-辐射模型，通过钛K壳层X射线光谱诊断惯性约束聚变中的受激拉曼散射，该方法对超热电子敏感，并与实验吻合，可作为传统背向散射诊断的补充。
中文摘要 AI 辅助
在惯性约束聚变（ICF）中，对受激拉曼散射（SRS）的精确表征仍然是一个关键挑战，因为SRS不仅散射激光能量，还会产生超热电子，这些电子预热燃料并降低内爆性能。传统的背向散射诊断提供SRS的直接测量，但无法收集全部散射光信号，限制了SRS强度的精确表征。利用具有双麦克斯韦电子分布的非局域热力学平衡碰撞-辐射模型，我们系统地研究了超热电子如何改变钛K壳层X射线发射光谱。在相对较低的体电子温度下，光谱对超热电子分数表现出高灵敏度，使其特别适用于ICF早期阶段超热电子的诊断，此时即使少量的超热电子群体也可能损害燃料压缩。计算光谱与Nova激光装置的实验测量结果吻合良好，推断的超热电子分数与独立测量的SRS损耗相比，与Glenzer等人[Phys. Rev. Lett. 81, 365 (1998)]的原始光谱分析相比，显示出更好的一致性。这些结果表明，K壳层光谱结合精确的NLTE碰撞-辐射建模，为激光产生等离子体中的SRS强度提供了可靠的探针。因此，该方法可扩展到SRS强度的空间分辨诊断，为传统背向散射诊断提供有前景的补充。
英文摘要
Accurate characterization of stimulated Raman scattering (SRS) remains a critical challenge in inertial confinement fusion (ICF), as SRS not only scatters laser energy but also generates suprathermal electrons that preheat the fuel and degrade implosion performance. Conventional backscatter diagnostics provide direct measurements of SRS but cannot collect the entire scattered-light signal, limiting the accurate characterization of SRS strength. Using a non-local thermodynamic equilibrium collisional-radiative model with a double-Maxwellian electron distribution, we systematically investigate how suprathermal electrons modify the titanium \textit{K}-shell x-ray emission spectra. The spectra exhibit high sensitivity to the suprathermal-electron fraction at relatively low bulk electron temperatures, making them particularly suitable for diagnosing suprathermal electrons during the early stage of ICF, when even a small suprathermal-electron population can compromise fuel compression. The calculated spectra reproduce experimental measurements from the Nova Laser Facility with good agreement, and the inferred suprathermal-electron fractions show improved consistency with independently measured SRS losses compared with the original spectral analysis by Glenzer~\href{https://doi.org/10.1103/PhysRevLett.81.365} {\text{[S. H. Glenzer \textit{et al}., Phys. Rev. Lett. \textbf{81}, 365(1998)]}}. These results demonstrate that \textit{K}-shell spectroscopy, combined with accurate NLTE collisional-radiative modeling, provides a reliable probe of SRS strength in laser-produced plasmas. Hence, this approach may be extended to spatially resolved diagnosis of SRS strength, offering a promising complement to conventional backscatter diagnostics.
