Characterization of laser-induced plasmas under simulated conditions of selected celestial bodies

对近天体的探索代表了各种技术/研究领域的持久兴趣。这包括地质调查，特别是对火星、月球甚至小行星表面的元素分析。为此，人们开发了各种策略，其中激光诱导击穿光谱（LIBS）技术已被证明是最方便的方法之一。LIBS的本质是将激光脉冲聚焦在样品表面，烧蚀目标材料的一小部分，诱导等离子体，并收集其光学发射以进行进一步的光谱研究。然而，激光-物质相互作用和随后的激光烧蚀受到被测样品的物理/化学基质效应和实验参数的显著影响，包括被测天体的环境条件（实验室缓冲气体、大气或天体表面的超高真空）。为了提供可靠的LIBS分析，必须了解烧蚀，等离子体形成及其演变的过程。该项目的主要范围是根据上述天体的环境条件描述上述过程。这个项目的新颖性可以概括如下。A)在特征信号（例如，显示等离子体形状和非均匀性，冲击波膨胀速度）的相关性方面的新方法，以更准确地描述（例如，等离子体内部的温度和电子密度分布）LIP模型的时空演变及其与数值模型的比较。B)一种基于机器学习的方法，能够将在类地条件下获得的LIBS数据传输到类火星和类月球条件下，这超出了目前的技术水平。C)创新应用时间分辨FTIR光谱法对LIP进行表征，提供烧蚀等离子体中形成的原子和分子种类的详细信息（能够解析多个重叠分子带的旋转振动跃迁以及原子谱线的超精细结构）。D)等离子体模型解释了等离子体羽流中的化学转变，并允许预测等离子体发射光谱，这与实验直接可比，是独特而新颖的。它将允许优化复杂交织的实验参数，而无需进行繁琐和耗时的优化实验。

The exploration of near celestial bodies represents a persisting interest for various techniques/research fields. This involves geological survey, particularly the elemental analysis of surface of, e.g., Mars, Moon and even of asteroids. For this purpose, various strategies were developed, among which the laser-induced breakdown spectroscopy (LIBS) technique has proven itself as one of the most convenient approaches. The utilization of LIBS in remote and even stand-off applications is enabled from its essence, focusing a laser pulse on the sample surface, ablating a fraction of the target material, inducing a plasma, and collecting its optical emission for further spectroscopic investigation. However, laser-matter interactions and the consequent laser ablation is significantly influenced by physical/chemical matrix effects of the examined sample and experimental parameters, incl. the ambient conditions (buffer gas in laboratory, atmosphere, or ultra-high vacuum on celestial body surface) on the considered celestial bodies. To provide reliable LIBS analysis, it is mandatory to understand the processes of ablation, plasma formation and its evolution. The main scope of the project is to describe mentioned processes with respect to the ambient conditions of said celestial bodies. The novelty of the project can be summarized as follows. A) Novel approaches in the correlation of characteristics signals (e.g., showing plasma shape and heterogeneity, speed of the shockwave expansion) for more accurate description (e.g., temperature and electron density distributions within the plasma bulk) of spatial-temporal evolution of LIP model and their comparison with numerical models. B) A machine-learning based approach enabling the transfer of the LIBS data obtained under Earth-like conditions to Mars- and Moon-like conditions that goes beyond the current state of the art. C) Innovative application of time-resolved FTIR spectrometry for LIP characterization that provides detailed information about the atomic and molecular species forming in the ablation plasma (with ability to resolve the rotation vibration transitions of multiple overlapping molecular bands as well as the hyperfine structure of atomic spectral lines). D) Plasma model that accounts for chemical transformations in the plasma plume and allows the prediction of plasma emission spectra, which are directly comparable to experiment, is unique and novel. It will allow the optimization of complexly intertwined experimental parameters without making tedious and time-consuming optimization experiments.