Acoustic monitoring of laser-induced phase transitions in minerals - implication for Mars exploration with SuperCam
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-12-15 |
| Journal | Scientific Reports |
| Authors | Baptiste Chide, Olivier Beyssac, M. Gauthier, Karim Benzerara, ImĂšne Esteve |
| Institutions | Los Alamos National Laboratory, Institut de minéralogie, de physique des matériaux et de cosmochimie |
| Citations | 15 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: MPCVD Diamond for Advanced LIBS/Acoustic Sensing
Section titled âTechnical Documentation & Analysis: MPCVD Diamond for Advanced LIBS/Acoustic SensingâExecutive Summary
Section titled âExecutive SummaryâThis research demonstrates a novel application of acoustic monitoring alongside Laser-Induced Breakdown Spectroscopy (LIBS) to detect instantaneous, laser-induced phase transitions in materials, with direct implications for planetary exploration (Mars SuperCam).
- Core Achievement: Acoustic signal amplitude provides a real-time, remote indicator of mineral phase change (e.g., Hematite to Magnetite, Diamond to Amorphous Carbon) occurring within the first few laser shots.
- Physical Mechanism: The phase transition dramatically alters the targetâs physical properties, specifically reducing the optical penetration depth ($d_{opt}$) and thermal penetration depth ($\delta_{th}$).
- Diamond as a Model System: Natural diamond, initially highly transparent to the 1067 nm LIBS laser ($d_{opt}$ up to 2.2 x 108 nm), transforms into highly absorptive amorphous carbon ($d_{opt}$ ~41 nm).
- Acoustic Amplification: This transformation increases the laser-matter coupling efficiency, resulting in a sharp increase in the acoustic signal amplitude (up to a factor of 5 for diamond) over the first 5 shots.
- 6CCVD Value Proposition: High-purity, low-defect MPCVD Single Crystal Diamond (SCD) from 6CCVD is the ideal material for replicating and extending these fundamental studies on laser-matter interaction physics due to its superior optical transparency and controlled material properties compared to natural samples.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the analysis of laser-matter interaction and material properties:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Laser Wavelength | 1067 | nm | LIBS infrared pulse |
| Laser Pulse Duration | 5 | ns | LIBS system (ChemCam Mast-Unit) |
| Laser Energy Deposited | ~10 | mJ | Per pulse on target |
| Irradiance on Target | > 1 | GWcm-2 | SuperCam setup |
| SCD Optical Penetration (dopt) | 1.3 x 107 to 2.2 x 108 | nm | Diamond (highly transparent to 1067 nm) |
| Amorphous Carbon dopt | 41 | nm | Post-transition material (highly absorptive) |
| Hematite Thermal Penetration ($\delta_{th}$) | 140 | nm | Fe2O3 |
| Magnetite Thermal Penetration ($\delta_{th}$) | 92 | nm | Fe3O4 |
| Acoustic Signal Increase (Diamond) | Factor of 5 | N/A | Increase over the first 5 shots (Diamond -> Amorphous Carbon) |
| Acoustic Signal Increase (Iron Oxides) | ~25 | % | Increase over the first 5 shots (Hematite/Goethite -> Magnetite) |
| Martian Atmosphere Pressure | 6 | mbar | Simulated testing environment |
Key Methodologies
Section titled âKey MethodologiesâThe experiment utilized a specialized LIBS and acoustic test bench simulating Martian conditions to analyze phase transitions induced by high-irradiance laser pulses.
- LIBS System: Utilized the ChemCam Mast-Unit Engineering Model (1067 nm, 5 ns pulse duration) fired at a frequency of 3 Hz.
- Atmosphere Control: Samples were housed in a vacuum chamber filled with a controlled Mars atmosphere gas mixture (95.7% CO2, 2.7% N2, 1.6% Ar) maintained at 6 mbar pressure.
- Acoustic Data Acquisition: A Knowles Electret condenser microphone (EK-23132) recorded the LIBS burst continuously at 200 kHz. Acoustic energy (Pa2.s) was computed from the square value of the acoustic waveform over the compression phase.
- Ablation Sequence: Bursts of 30 laser shots were performed, with specific focus on 1 to 5 cumulative shots to isolate the onset of phase transition and its effect on acoustic coupling.
- Post-Ablation Characterization: Laser-induced craters were analyzed using:
- Raman Spectroscopy (532 nm): Used for phase identification (e.g., confirming Magnetite formation and Diamond amorphization). Hyperspectral mapping tracked the percentage of transformed material.
- Scanning Electron Microscopy (SEM): Used to analyze crater morphology, microtexture, and the thickness of the molten/recrystallized layers.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe study highlights the critical role of material purity, optical transparency, and thermal properties in determining laser-matter coupling efficiencyâa domain where 6CCVDâs MPCVD diamond excels. The natural diamond used in this research contained impurities and defects; 6CCVD offers engineered diamond solutions that provide superior control and performance for advanced LIBS and acoustic sensing applications.
| Research Requirement | 6CCVD Solution & Value Proposition |
|---|---|
| Ultra-High Transparency Substrates | Optical Grade Single Crystal Diamond (SCD): The paper confirms that diamondâs extreme transparency at 1067 nm is key to the acoustic phenomenon. 6CCVD supplies high-purity, low-defect SCD (up to 500 ”m thick) that minimizes initial absorption, providing a pristine, reproducible platform for studying fundamental laser-matter interaction physics and phase transitions. |
| Precision Surface Finish | SCD Polishing (Ra < 1 nm): Surface roughness significantly impacts laser-matter interaction. Our SCD is polished to an industry-leading roughness of Ra < 1 nm, ensuring highly planar surfaces necessary for precise, repeatable ablation experiments and minimizing surface-defect-induced coupling. |
| Custom Dimensions & Integration | Large Area MPCVD Diamond: We offer custom plates and wafers up to 125 mm (PCD) and large-area SCD. This capability supports the development of next-generation planetary instruments, allowing for larger optical windows, detector substrates, or acoustic sensor components. |
| Controlled Electrical/Thermal Properties | Boron-Doped Diamond (BDD): For applications requiring controlled thermal dissipation ($\delta_{th}$ control) or electrical conductivity (e.g., electrochemical sensors or robust contacts), 6CCVD supplies BDD films and substrates with tunable doping levels. |
| Sensor Integration & Packaging | In-House Metalization Services: The integration of diamond into complex sensor packages often requires custom contacts. 6CCVD offers internal metalization capabilities (Au, Pt, Pd, Ti, W, Cu) tailored to specific adhesion and environmental requirements (e.g., high-vacuum or extreme temperature environments). |
| Global Logistics Support | Worldwide Shipping: 6CCVD ensures reliable, global delivery of sensitive diamond materials (DDU default, DDP available), supporting international research collaborations and space mission supply chains. |
Engineering Support: 6CCVDâs in-house PhD team specializes in optimizing MPCVD diamond properties for extreme environments and advanced sensing. We can assist researchers in selecting the optimal SCD or PCD grade, thickness (0.1 ”m to 500 ”m), and surface preparation for similar LIBS/Acoustic monitoring projects or other high-energy laser applications.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.