Laser-Induced Breakdown Spectroscopy for In-Cylinder Equivalence Ratio Measurements in Laser-Ignited Natural Gas Engines

2009 ◽  
Vol 63 (5) ◽  
pp. 549-554 ◽  
Author(s):  
Sachin Joshi ◽  
Daniel B. Olsen ◽  
Cosmin Dumitrescu ◽  
Paulius V. Puzinauskas ◽  
Azer P. Yalin
Keyword(s):  
Natural Gas ◽  
Equivalence Ratio ◽  
Yttrium Aluminum Garnet ◽  
Laser Energy ◽  
Energy Levels ◽  
Wide Band ◽  
Laser Induced Breakdown Spectroscopy ◽  
Breakdown Spectroscopy ◽  
Spark Plug ◽  
Laser Induced Breakdown

In this contribution we present the first demonstration of simultaneous use of laser sparks for engine ignition and laser-induced breakdown spectroscopy (LIBS) measurements of in-cylinder equivalence ratios. A 1064 nm neodynium yttrium aluminum garnet (Nd:YAG) laser beam is used with an optical spark plug to ignite a single cylinder natural gas engine. The optical emission from the combustion initiating laser spark is collected through the optical spark plug and cycle-by-cycle spectra are analyzed for Hα (656 nm), O (777 nm), and N (742 nm, 744 nm, and 746 nm) neutral atomic lines. The line area ratios of Hα/O777, Hα/N746, and Hα/Ntot (where Ntot is the sum of areas of the aforementioned N lines) are correlated with equivalence ratios measured by a wide band universal exhaust gas oxygen (UEGO) sensor. Experiments are performed for input laser energy levels of 21 mJ and 26 mJ, compression ratios of 9 and 11, and equivalence ratios between 0.6 and 0.95. The results show a linear correlation ( R2 > 0.99) of line intensity ratio with equivalence ratio, thereby suggesting an engine diagnostic method for cylinder resolved equivalence ratio measurements.

scholarly journals Time-Gated Single-Shot Picosecond Laser-Induced Breakdown Spectroscopy (ps-LIBS) for Equivalence-Ratio Measurements

2020 ◽  
Vol 74 (3) ◽  
pp. 340-346 ◽  
Author(s):  
Mark Gragston ◽  
Paul Hsu ◽  
Anil Patnaik ◽  
Zhili Zhang ◽  
Sukesh Roy
Keyword(s):  
High Pressure ◽  
Atmospheric Pressure ◽  
Equivalence Ratio ◽  
Laser Energy ◽  
Picosecond Laser ◽  
Laser Induced Breakdown Spectroscopy ◽  
Single Shot ◽  
Plasma Emission ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown

Time-gated picosecond laser-induced breakdown spectroscopy (ps-LIBS) for the determination of local equivalence ratios in atmospheric-pressure adiabatic methane–air flames is demonstrated. Traditional LIBS for equivalence-ratio measurements employ nanosecond (ns)-laser pulses, which generate excessive amounts of continuum, reducing measurement accuracy and precision. Shorter pulse durations reduce the continuum emission by limiting avalanche ionization. Furthermore, by contrast the use of femtosecond lasers, plasma emission using picosecond-laser excitation has a high signal-to-noise ratio (S/N), allowing single-shot measurements suitable for equivalence-ratio determination in turbulent reacting flows. We carried out an analysis of the dependence of the plasma emission ratio Hα (656 nm)/NII (568 nm) on laser energy and time-delay for optimization of S/N and minimization of measurement uncertainties in the equivalence ratios. Our finding shows that higher laser energy and shorter time delay reduces measurement uncertainty while maintaining high S/N. In addition to atmospheric-pressure flame studies, we also examine the stability of the ps-LIBS signal in a high-pressure nitrogen cell. The results indicate that the plasma emission and spatial position could be stable, shot-to-shot, at elevated pressure (up to 40 bar) using a lower excitation energy. Our work shows the potential of using ps-duration pulses to improve LIBS-based equivalence-ratio measurements, both in atmospheric and high-pressure combustion environments.

Characterization of Amethysts from Sukamara, Central Kalimantan, Using Laser-Induced Breakdown Spectroscopy (LIBS)

2020 ◽  
Vol 1 (2) ◽  
pp. 5-8
Author(s):  
Komang Gde Suastika, Heri Suyanto, Gunarjo, Sadiana, Darmaji
Keyword(s):  
Emission Intensity ◽  
Laser Energy ◽  
Emission Spectra ◽  
Atomic Emission ◽  
Laser Induced Breakdown Spectroscopy ◽  
Chemical Formula ◽  
Central Kalimantan ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown

Abstract - Laser-Induced Breakdown Spectroscopy (LIBS) is one method of atomic emission spectroscopy using laser ablation as an energy source. This method is used to characterize the type of amethysts that originally come from Sukamara, Central Kalimantan. The result of amethyst characterization can be used as a reference for claiming the natural wealth of the amethyst. The amethyst samples are directly taken from the amethyst mining field in the District Gem Amethyst and consist of four color variations: white, black, yellow, and purple. These samples were analyzed by LIBS, using laser energy of 120 mJ, delay time detection of 2 μs and accumulation of 3, with and without cleaning. The purpose of this study is to determine emission spectra characteristics, contained elements, and physical characteristics of each amethyst sample. The spectra show that the amethyst samples contain some elements such as Al, Ca, K, Fe, Gd, Ba, Si, Be, H, O, N, Cl and Pu with various emission intensities. The value of emission intensity corresponds to concentration of element in the sample. Hence, the characteristics of the amethysts are based on their concentration value. The element with the highest concentration in all samples is Si, which is related to the chemical formula of SiO2. The element with the lowest concentration in all samples is Ca that is found in black and yellow amethysts. The emission intensity of Fe element can distinguish between white, purple, and yellow amethyst. If Fe emission intensity is very low, it indicates yellow sample. Thus, we may conclude that LIBS is a method that can be used to characterize the amethyst samples.Key words: amethyst, impurity, laser-induced, breakdown spectroscopy, characteristic, gemstones

scholarly journals Determination of Species Concentrations of Ti-6Al-4V Titanium Alloys using Calibration Free Laser Induced Breakdown Spectroscopy

2018 ◽  
Vol 3 (8) ◽  
pp. 50 ◽  
Author(s):  
Tagreed K. Hamad ◽  
Hussein Thamer Salloom
Keyword(s):  
Energy Levels ◽  
Surface Hardness ◽  
Plasma Temperature ◽  
Hardness Test ◽  
Spectral Lines ◽  
Laser Induced Breakdown Spectroscopy ◽  
Boltzmann Plot ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
Calibration Free

In this study, Calibration-free Laser-induced breakdown spectroscopy (CF-LIBS) was applied to quantitatively analyze the elemental composition of Ti-6Al-4V titanium based alloy samples with no need for matrix-matched calibration procedure. Nd:YAG pulsed laser operating at a wavelength of 1064 nm was focused onto the sample to generate plasma. The spectrum of plasma was recorded using spectrophotometer then compared to NIST spectral lines to determine characteristic wavelengths, energy levels and other spectroscopic parameters. The values of plasma temperature obtained using Boltzmann plot for four examined samples ranged from 7439 to 6826 K while the electron density for each element was determined using Boltzmann-Saha equation. The concentration of Ti, Al, V and Fe has been determined and were within the samples nominal concentrations obtained from XRF analysis.  The calculated average relative errors of Ti, Al, V and Fe were 0.39%, 4.38%, 4.94 % and 8.2 %, respectively. Finally, there was a direct proportionality relation between the ratio of ionic to neutral emission lines of Ti for four samples and the surface hardness values measured mechanically using Vickers hardness test. The ratio at   had the best linear regression value (R2=0.95) which indicates the best correlation with surface hardness.

scholarly journals Investigation of compositional analysis and physical properties for Ni-Cr-Nb alloys using laser-induced breakdown spectroscopy

2021 ◽  
Vol 51 (3) ◽  
Author(s):  
Hussein Salloom ◽  
Tagreed Hamad
Keyword(s):  
Thermal Conductivity ◽  
Laser Energy ◽  
Plasma Temperature ◽  
Compositional Analysis ◽  
Spectral Lines ◽  
Laser Induced Breakdown Spectroscopy ◽  
Elemental Content ◽  
Empirical Formulas ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown

In this work, laser-induced breakdown spectroscopy (LIBS) analysis is optimized for direct estimation of elemental composition, thermal conductivity and hardness for Ni-Cr-Nb alloys. These alloys were chosen with a variable elemental content of niobium and chromium. The influence of laser energy and shot numbers on measuring line intensity was investigated. Based on the ratio between two spectral lines, calibration curves were formed to estimate the element concentration and LIBS results were confirmed with related energy-dispersive X-ray spectroscopy (EDS) data. Hardness and thermal conductivity estimation using LIBS were done by measuring the ratio between two spectral lines, plasma excitation temperature and electron density for different samples. Semi-empirical formulas correlated hardness and thermal conductivity with plasma temperature were established.

Quantitative Analysis of Metal Film by Laser-Induced Breakdown Spectroscopy (LIBS)

2011 ◽  
Vol 179-180 ◽  
pp. 1183-1186 ◽  
Author(s):  
Dong Qing Yuan ◽  
Jian Ting Xu
Keyword(s):  
Quantitative Analysis ◽  
Metal Film ◽  
Laser Energy ◽  
Laser Induced Breakdown Spectroscopy ◽  
Optimum Time ◽  
Pulsed Nd:Yag Laser ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
Calibration Free ◽  
The Relationship

The plasma was generated by focusing a pulsed Nd:YAG laser at 1064nm and 10ns on the surface of ITO. We investigated the relationship between the signal intensity of LIBS and the pulse energy of laser, and found the signal of the analyze lines of In and Sn increased with the laser energy enhanced proportional. A series of measurements were made to found the optimum time delay between the laser pulse and the beginning of the LIBS spectra acquisition. Through calibration-free method we obtain the temperature of plasma,at the same time we measured the content of In and Sn by the program which writed with matlab.

scholarly journals Lean partially premixed turbulent flame equivalence ratio measurements using laser-induced breakdown spectroscopy

Fuel ◽  
2019 ◽  
Vol 237 ◽  
pp. 320-334 ◽  
Author(s):  
Tawfik Badawy ◽  
Mahmoud Hamza ◽  
Mohy S. Mansour ◽  
Abdel-Hafez H. Abdel-Hafez ◽  
Hisham Imam ◽  
...  
Keyword(s):  
Equivalence Ratio ◽  
Turbulent Flame ◽  
Laser Induced Breakdown Spectroscopy ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
Partially Premixed ◽  
Premixed Turbulent Flame
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