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

Abstract

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. Published by AIP Publishing.