Laser-induced breakdown thermometry via time-of-arrival measurements of associated acoustic waves

In this study, laser-induced breakdown thermometry based on time-of-arrival measurements of associated acoustic waves is proposed. Two laser-induced breakdowns were produced, separated by a known distance, and the arrivals of the resulting acoustic waves were measured using a high-frequency-response microphone installed in the same plane and line as the breakdowns. Because the speed of acoustic waves is a function of temperature, the temperatures of the region between and including the laser-induced breakdowns could be determined by measuring the arrival times of the acoustic waves from the two breakdowns. Experiments were conducted while varying the temperature of air from 300 to 1000 K, and the results were compared to those measured using a k-type thermocouple. The proposed method becomes calibration-free once the species composition is given. The temperature was measured with an accuracy of ±16 K under the studied conditions.In this study, laser-induced breakdown thermometry based on time-of-arrival measurements of associated acoustic waves is proposed. Two laser-induced breakdowns were produced, separated by a known distance, and the arrivals of the resulting acoustic waves were measured using a high-frequency-response microphone installed in the same plane and line as the breakdowns. Because the speed of acoustic waves is a function of temperature, the temperatures of the region between and including the laser-induced breakdowns could be determined by measuring the arrival times of the acoustic waves from the two breakdowns. Experiments were conducted while varying the temperature of air from 300 to 1000 K, and the results were compared to those measured using a k-type thermocouple. The proposed method becomes calibration-free once the species composition is given. The temperature was measured with an accuracy of ±16 K under the studied conditions.

[1]  James R. Gord,et al.  Recent advances in coherent anti-Stokes Raman scattering spectroscopy: Fundamental developments and applications in reacting flows , 2010 .

[2]  Manfred Aigner,et al.  Optical and spectroscopic diagnostics of laser-induced air breakdown and kerosene spray ignition , 2015 .

[3]  P. P. Kiran,et al.  Effect of pulse duration on the acoustic frequency emissions during the laser-induced breakdown of atmospheric air. , 2016, Applied optics.

[4]  C. Leela,et al.  Effect of laser intensity on temporal and spectral features of laser generated acoustic shock waves: ns versus ps laser pulses. , 2017, Applied optics.

[5]  Walter R. Lempert,et al.  Laser Rayleigh scattering , 2001 .

[6]  E. Salerno,et al.  An acoustic pyrometer system for tomographic thermal imaging in power plant boilers , 1996 .

[7]  Ming-Shing Young,et al.  High precision, fast ultrasonic thermometer based on measurement of the speed of sound in air , 2002 .

[8]  G. Taylor.  The formation of a blast wave by a very intense explosion I. Theoretical discussion , 1950, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[9]  Johannes Kiefer,et al.  Laser-induced breakdown flame thermometry , 2012 .

[10]  Keith Attenborough,et al.  Characteristics and application of laser-generated acoustic shock waves in air , 2004 .

[11]  R. Hanson,et al.  Diode-Laser Absorption Sensor for Line-of-Sight Gas Temperature Distributions. , 2001, Applied optics.

[12]  M. Lackner.  TUNABLE DIODE LASER ABSORPTION SPECTROSCOPY (TDLAS) IN THE PROCESS INDUSTRIES – A REVIEW , 2007 .