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Laser-Induced Breakdown Spectroscopy for the Exploration of Mars: Analysis of Molecular Emissions and Spatial Characterization of the Plasma

Vogt, David (2020) Laser-Induced Breakdown Spectroscopy for the Exploration of Mars: Analysis of Molecular Emissions and Spatial Characterization of the Plasma. Dissertation.

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Official URL: https://edoc.hu-berlin.de/handle/18452/21798

Abstract

In this thesis, laser-induced breakdown spectroscopy (LIBS) is investigated in the context of the robotic exploration of Mars. In LIBS, the plasma formed by laser-ablated sample material is analyzed spectroscopically. Since 2012, it is employed by the ChemCam instrument on board the Mars rover Curiosity to analyze rocks and soil on the Martian surface. The technique will also be used in NASA's Mars 2020 mission and in the Chinese HX-1 mission, which are both scheduled to launch to Mars in 2020. The first two studies are concerned with emissions of molecules that form in the laser-induced plasma. These can be used to detect chlorine and fluorine, which are of geological interest for Mars. In the first study, MgCl and CaCl emissions are investigated for the detection and quantification of chlorine in Martian atmospheric conditions. Only the CaCl signal is found to be intense enough for this purpose. The CaCl signal is found to be skewed towards low chlorine concentrations, which is explained by a non-equilibrium model of the laser-induced plasma. In the second study, the emissions of CaCl and CaF are compared. The same model is used to describe the dependence of both signals on the respective reactant concentrations. Strong matrix effects are observed that affect the observed intensities. In the final part of the thesis the plasma imaging setup that was developed in the context of this thesis is presented. It enables spatially resolved measurements of the plasma emission spectra. First results show that CaCl and CaF emissions are confined close to the plasma center, likely because rarefaction leads to a low-temperature center in which molecules can form. Atomic emissions of hydrogen, carbon, and oxygen are more stable at the plasma front and show signs of vorticity, indicating a complex temperature distribution and a strong influence of flows within the plasma.

Item URL in elib:https://elib.dlr.de/131240/
Document Type:Thesis (Dissertation)
Title:Laser-Induced Breakdown Spectroscopy for the Exploration of Mars: Analysis of Molecular Emissions and Spatial Characterization of the Plasma
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Vogt, DavidDavid.Vogt (at) dlr.deUNSPECIFIED
Date:15 January 2020
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Number of Pages:183
Status:Published
Keywords:Mars Spectroscopy Molecules Imaging Halogens Geology
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Technology
DLR - Research area:Raumfahrt
DLR - Program:R SY - Technik für Raumfahrtsysteme
DLR - Research theme (Project):R - Vorhaben Robotischer Wissenschafts-Explorer
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Optical Sensor Systems > Terahertz and Laser Spectroscopy
Deposited By: Vogt, David
Deposited On:28 Jan 2020 08:42
Last Modified:28 Jan 2020 08:42

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