scholarly journals A Review of Femtosecond Laser-Induced Emission Techniques for Combustion and Flow Field Diagnostics

2019 ◽  
Vol 9 (9) ◽  
pp. 1906 ◽  
Author(s):  
Bo Li ◽  
Dayuan Zhang ◽  
Jixu Liu ◽  
Yifu Tian ◽  
Qiang Gao ◽  
...  
Keyword(s):  
Flow Field ◽  
Femtosecond Laser ◽  
Femtosecond Lasers ◽  
Diagnostic Techniques ◽  
Nonlinear Spectroscopy ◽  
Plasma Spectroscopy ◽  
Breakdown Spectroscopy ◽  
Two Photon ◽  
Combustion Diagnostics ◽  
Laser Induced Breakdown

The applications of femtosecond lasers to the diagnostics of combustion and flow field have recently attracted increasing interest. Many novel spectroscopic methods have been developed in obtaining non-intrusive measurements of temperature, velocity, and species concentrations with unprecedented possibilities. In this paper, several applications of femtosecond-laser-based incoherent techniques in the field of combustion diagnostics were reviewed, including two-photon femtosecond laser-induced fluorescence (fs-TPLIF), femtosecond laser-induced breakdown spectroscopy (fs-LIBS), filament-induced nonlinear spectroscopy (FINS), femtosecond laser-induced plasma spectroscopy (FLIPS), femtosecond laser electronic excitation tagging velocimetry (FLEET), femtosecond laser-induced cyano chemiluminescence (FLICC), and filamentary anemometry using femtosecond laser-extended electric discharge (FALED). Furthermore, prospects of the femtosecond-laser-based combustion diagnostic techniques in the future were analyzed and discussed to provide a reference for the relevant researchers.

scholarly journals Equivalence Ratio Measurements in CH4/Air Gases Based on the Spatial Distribution of the Emission Intensity of Femtosecond Laser-Induced Filament

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 2022
Author(s):  
Ming Li ◽  
Jiangpeng Gu ◽  
Dayuan Zhang ◽  
Qiang Gao ◽  
Bo Li
Keyword(s):  
Spatial Distribution ◽  
Flow Field ◽  
Femtosecond Laser ◽  
Emission Intensity ◽  
Equivalence Ratio ◽  
Femtosecond Lasers ◽  
Diagnostic Techniques ◽  
Spatially Resolved ◽  
Combustion Diagnostics ◽  
Laser Filamentation

Femtosecond lasers have been used in combustion diagnostics. Based on the characteristics of femtosecond laser filamentation, many diagnostic techniques have been developed. Here, we propose a method, based on femtosecond laser filamentation, for equivalence ratio measurements in CH4/air gases. By measuring the spatially resolved spectra of the femtosecond laser-induced filament, we found that the variation of the equivalence ratio in the flow field would affect the spatial distribution of the emission intensity of femtosecond laser-induced filament. On this basis, the equivalence ratio was calibrated by using the relative spatial positions of N2 (337 nm) and C2 (516.5 nm) signals in the filament. This method overcomes the interference of local air disturbance, having lower measurement uncertainty.

Nanosecond laser-induced breakdown assisted by femtosecond laser pre-ionization in air: the effect on spatial resolution and continuous radiation

2020 ◽  
Vol 92 (2) ◽  
pp. 20701
Author(s):  
Bo Li ◽  
Xiaofeng Li ◽  
Zhifeng Zhu ◽  
Qiang Gao
Keyword(s):  
Femtosecond Laser ◽  
Spatial Resolution ◽  
Laser Induced Breakdown Spectroscopy ◽  
Nanosecond Laser ◽  
Breakdown Threshold ◽  
Powerful Technique ◽  
Breakdown Spectroscopy ◽  
Continuous Radiation ◽  
Laser Induced Breakdown

Laser-induced breakdown spectroscopy (LIBS) is a powerful technique for quantitative diagnostics of gases. The spatial resolution of LIBS, however, is limited by the volume of plasma. Here femtosecond-nanosecond dual-pulsed LIBS was demonstrated. Using this method, the breakdown threshold was reduced by 80%, and decay of continuous radiation was shortened. In addition, the volume of the plasma was shrunk by 85% and hence, the spatial resolution of LIBS was significantly improved.

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