Research on LIBS at IFPiLM has roots in development work on mastering thermonuclear energy in the MCF (Magnetic Confinement Fusion) variant, in which it became necessary to develop a method for removing fuel (deuterium and tritium) accumulating on the surface of the inner wall of the experimental chamber. Over time, the research at IFPiLM went beyond the efforts related to thermonuclear fusion and included the analysis of other materials as well as enriching them with elements of machine learning (ML – Machine Learning).
A variant of the LIBS method developed at IFPiLM is DP (Dual Pulse) LIBS, thanks to which it is possible to obtain much better signal dynamics, which minimizes measurement errors.
In 2020, the LIBS laboratory was separated from the Plasma Research Laboratory with Spectroscopic Methods as the Laboratory of Laser-Excited Plasma Spectroscopy.
Although work on the adaptation of the LIBS technique to the needs of thermonuclear fusion technology continues to be an important part of the laboratory’s activities, other research is also being carried out to broaden the scope of competence. The main emphasis is currently placed on the adaptation of machine learning methods, in particular artificial neural networks, for the analysis of the obtained spectra.
During numerous experiments, many spectra were collected, not only for materials used in fusion technology, but also for other materials such as metals and their alloys (including various steel grades), plastics, soils, minerals and organic samples. For some of them, e.g. steel, analyzes were carried out using machine learning methods, which confirmed the effectiveness of classification algorithms for both simulation and experimental data.
The laboratory has complete equipment for conducting spectrometric measurements using the dual-pulse LIBS method. The LOTIS TII LS-2134D system is used as the source of laser pulses. It allows the generation of pulses with a duration (FWHM) of 12-15 ns, energy up to 200 mJ and repetition rates up to 10 Hz. The pulse interval can be set in the range of 0-80 us with a resolution of 1 ns. Detailed information is available on the manufacturer’s website: https://www.lotis-tii.com/eng/productid16.php
The spectrometer used in IFPiLM is the MECHELLE 5000 equipped with the ISTAR image intensifier. It enables the observation of the spectrum in the range from 200 to 900 nm with a resolution Dl/l of 5000. Thanks to equipping the spectrometer with an image intensifier, it is possible to observe the phenomena occurring with the emission of low signal level, as well as to obtain a very good time resolution of measurements. The synchronization is very precise thanks to the equipment of the device with a DDG (Digital Delay Generator). It allows you to adjust both the delay time and the gate opening with nanosecond resolution.
The data obtained from the spectrometer is processed and analyzed using Python programs created by the team, thanks to which it is possible to batch conversion and calibration of the intensity, and then adjust the line and determine the temperature and electron concentration.
More detailed information about the spectrometer can be found on the manufacturer’s website: https://andor.oxinst.com/products/mechelle-spectrograph/mechelle-5000
Laser Induced Breakdown Spectroscopy
In order to build a system fully adapted to work outside the laboratory, in 2020 the originally available in OEM version IBSEN FREEDOM UV-NIR FSA-380 spectrometer was adapted. It is an economical solution that offers a lower resolution, but is more compact and mobile, with the possibility of measuring in a wide spectral range. from 200 to 1100 nm. Its key advantages are the ease of building systems and low sensitivity to external factors, e.g. vibrations. Its use fully enables work outside the laboratory, also in the field.
- classification of any materials based on the original samples provided;
- detection of counterfeit materials;
- detection of contamination in materials;
- quantitative analysis of the content of specific components on the basis of calibration samples.
Laser Induced Breakdown Spectroscopy
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