Now showing 1 - 10 of 13
  • Placeholder Image
    Publication
    LIBS technique combined with blow gas and vacuum suction to remove particle cloud and enhance emission intensity during characterization of powder samples
    (01-07-2021)
    Rajavelu, Hemalaxmi
    ;
    ;
    The present study reports developing a bench-top Laser-Induced Breakdown Spectroscopy (LIBS) set up for the online analysis of powder samples without sample preparation. The powder particle blow-off during pulsed laser ablation was mitigated by adding a blow gas (an inert gas blown across the ablation surface) and a suction unit (for extraction of the blow gas and blown-off particle cloud) to the existing LIBS setup. The influence of a blow-gas combined with a suction unit on LIBS emission intensity from coal powder and flyash particles is studied in the present work. The effect of the blow gas flow rate and the suction pressure was studied on the LI-BS emission intensity and removal of the laser blown-off particle cloud. The combination gas flow at 2 lpm (liter per minute) flow rate and suction at 925 mbar (absolute) show an increase in the LIBS emission intensity and effective particle removal. The ratio of LIBS emission intensity of the powder sample and solid-target (pellet) sample improved from 0.25 without the Ar gas flow and the suction unit to 0.85, which is by a factor of 3.4 times with the proposed approach.
  • Placeholder Image
    Publication
    Broadband Photoacoustic Spectroscopy Technique in 2µm Wavelength Range for Sensing of Moisture and Carbon dioxide
    (01-01-2022)
    Saran Kumar, K.
    ;
    Esther Blesso Vidhya, Y.
    ;
    Selvaraj, Ramya
    ;
    ;
    Dual-wavelength, broadband photoacoustic technique is demonstrated for measurement of multiple gas species using a supercontinuum laser source. H2O vapor and CO2 measurements are demonstrated near 1920 and 2000 nm.
  • Placeholder Image
    Publication
    Real-time steam quality measurement using tunable diode laser absorption spectroscopy for process industries
    (01-01-2020)
    Chandra, Manish
    ;
    ;
    Process industry mostly uses steam as an indispensable source of energy. We are presenting a technique to measure quality in real time where single laser diode tuning capabilities is being utilized to generate arbitrary modulated laser intensity for non-absorbing and absorbing wavelength of water vapor and eliminates uses of multiple laser source.
  • Placeholder Image
    Publication
    Understanding the mechanism of molecular carbon emissions using time-resolved LIBS during online coal characterization
    (01-08-2020)
    Hemalaxmi, R.
    ;
    ;
    The origin, formation mechanism, and emission persistence time of atomic (C I) and molecular (CN Violet system and C2 Swan system) carbon emissions from coal plasma generated by laser ablation were studied using Time-resolved LIBS.
  • Placeholder Image
    Publication
    Hollow-core optical fiber-based laser-induced breakdown spectroscopy technique for the elemental analysis of pulverized coal
    (01-10-2022)
    Rajavelu, Hemalaxmi
    ;
    ;
    The present study proposed and demonstrated the feasibility of the fiber-based LIBS technique for the analysis of pulverized coal. A hollow-core fiber was employed to replace the air medium in the conventional LIBS setup for the delivery of high-power laser pulses to the target. It was observed that the hollow-core fiber could effectively deliver the laser energy for target ablation with a transmission efficiency of 50–60%. The LIBS spectra captured using the fiber LIBS technique prove that the addition of hollow-core fiber can upgrade the conventional LIBS technique into a remote characterization unit. Convincing results were obtained in terms of quantitative carbon measurement using the proposed approach.
  • Placeholder Image
    Publication
    Michelson Interferometry technique for the Dryness measurement of Saturated Steam
    (01-01-2022)
    Chandra, Manish
    ;
    ;
    Saturated steam dryness is derived from the refractive index measured using the Michelson Interferometer. For the measurement, the interdependence of the refractive index on wavelength, temperature, pressure, and density is used. The methodology is non-invasive and eliminates the use of multiple sources for dryness measurement.
  • Placeholder Image
    Publication
    Photoacoustic Approach Using a Broadband Laser Source for Sensing Carbon Monoxide and Carbon Dioxide
    (01-01-2022)
    Kumar, Saran K.
    ;
    Vidhya, Ester Blesso Y.
    ;
    Selvaraj, Ramya
    ;
    ;
    Supercontinuum laser-based broadband photoacoustic technique is demostrated for sensing CO, CO2 and H2O around 2µm. The detection limit of 6 ppm, 736 ppm and 20 ppb respectively, is attained with SNR of 3 dB.
  • Placeholder Image
    Publication
    Photoacoustic Approach Using a Broadband Laser Source for Sensing Carbon Monoxide and Carbon Dioxide
    (01-01-2022)
    Saran Kumar, K.
    ;
    Ester Blesso Vidhya, Y.
    ;
    Selvaraj, Ramya
    ;
    ;
    Supercontinuum laser-based broadband photoacoustic technique is demostrated for sensing CO, CO2 and H2O around 2 μm. The detection limit of 6 ppm, 736 ppm and 20 ppb respectively, is attained with SNR of 3 dB.
  • Placeholder Image
    Publication
    Dual Absorption Broadband Photoacoustic Technique to Eliminate Interference in Gas Mixtures
    (15-03-2023)
    Kumar, K. Saran
    ;
    Vidhya, Y. Esther Blesso
    ;
    Selvaraj, Ramya
    ;
    ;
    Nagendra, S. M.Shiva
    ;
    This article presents a dual-wavelength band broadband photoacoustic spectroscopy (BPAS) technique ideally suited to low-energy broadband sources for industrial and environmental multigas sensing applications. The broad spectral range of the supercontinuum source is used to cover a wide range of absorption bands of various gases. The major limitation in most of the gas sensors with broadband sources is the effect of interference between gases. This article proposes a dual-wavelength technique to eliminate the impact of cross sensitivity among gases. This sensor exhibits a comprehensive concentration measurement from parts per million (ppm) to % levels. The proposed technique showed a ±1.2% error between the calculated and calibrated concentration values. We achieved a minimum detection limit (MDL) of 0.4 and 0.7 ppm for methane (CH4) with an integration time of 142 and 200 s using 2315- and 1650-nm band, respectively, 0.3 and 1.8 ppm of ammonia (NH3) with an integration time of 100 and 48 s using 2315- and 2017-nm band, respectively, and also 2.6 ppm of carbon monoxide (CO) with an integration time of 71 s using the 2315-nm band.
  • Placeholder Image
    Publication
    Determination of Ash Content in Coal Using Laser-Induced Breakdown Spectroscopy with Multivariate Analysis
    (01-01-2021)
    Rajavelu, Hemalaxmi
    ;
    ;
    Laser-Induced Breakdown Spectroscopy (LIBS) technique is used to determine the emission intensity of inorganic elements, such as Si, Fe, Mg, Al, Ca, Na, and K in coal samples. The average emission intensity of the inorganic elements increases with the ash content of the coal sample with R2 = 0.82. Using the LIBS data, partial least square regression (PLSR)-based multivariate analysis was performed to determine the coal ash content. The PLS approach combined with the LIBS technique resulted in the coefficient of correlation R2 = 0.93, root-mean-square error RMSE = 3.5%, standard deviation SD = 11.7% and resolution = 3.7% corresponding to the reference ash data.