基于地外环境激光诱导等离子体演化机理的LIBS定量反演技术

激光诱导击穿光谱（LIBS）技术在深空探测领域的成功应用举世瞩目。我国首次火星探测工程就将使用LIBS技术来探测分析火星表面物质成分。LIBS在定性分析上虽已相对成熟，但在定量分析的准确度和稳定性上仍存在不足，这是因为对关键物理过程及其内在机理的认识还不够全面深入。本项目综合考虑热传导、高阶电离、激光等离子体相互作用、等离子体膨胀传播等过程，优化现有理论模型，采用PIC粒子模拟、求解欧拉方程、Saha-Eggert方程等多样化手段，深入研究激光诱导等离子体的形成及其在环境中的演化动力学过程，揭示火星大气环境下的等离子体演化宏观规律和微观机理，并结合实验，进一步完善理论成果。此外还将基于相关机理来构建优化LIBS光谱信号的方法体系，并有针对性地开发出准确度和稳定性更高的LIBS定量反演分析技术。本项目成果对我国研究火星具有重要科学意义，并为LIBS在其它地外环境下的应用提供理论基础和思路。

The successful application of laser-induced breakdown spectroscopy (LIBS) in deep space exploration has attracted worldwide attention. China’s first Mars explorer will employ LIBS to detect and analyze the chemical composition of different materials on Mars surface. Although LIBS is relatively mature in qualitative analysis, there are still some deficiencies in quantitative analysis, in terms of accuracy and stability. This is mainly due to the insufficiency of comprehensive and in-depth understanding of the involved key physical processes and the underlying mechanisms. In this project, we comprehensively consider the key processes including heat conduction, high-order ionization, laser-plasma interaction, plasma expansion and propagation, etc., and ameliorate some of the existing theoretical models. Through utilizing diversified computational means, such as Particle-In-Cell (PIC) simulation, solving Euler Equation and Saha-Eggert Equation, we will penetrate into the formation of laser-induced plasma and its subsequent evolution dynamics in ambient gases, and thereafter reveal the macroscopic laws and microscopic mechanisms of plasma evolution in Martian atmosphere. Our theoretical framework will be further improved based on our experimental verification results. In addition, a methodology for achieving LIBS spectra with higher signal quality will be constructed based on the relevant mechanisms, and a LIBS quantitative retrieval technology with higher accuracy and stability will be developed based on the higher-quality spectra. The expected achievements of this project will help to provide a better quantitative analysis of the Mars surface materials. They are of great scientific significance for China to the exploration and further study of Mars, and would provide theoretical basis and mentality for the extensive applications of LIBS in other extraterrestrial atmospheric environments.