Monitoring the deposited energy in laser-induced plasmas with an acoustic approach

Abstract

The monitoring of energy deposition behavior during the plasma formation process is the basis of recently developed laser-induced breakdown thermometry techniques. Utilizing the acoustic waveforms from laser-induced plasmas, a method to monitor the deposited energy was proposed. The linear relationships between the acoustic energy and the deposited energy were established under four different focal lengths. After the distortions in the sound propagation were corrected, the applicable range of this method was extended to a deposited energy from 10 to 240 mJ. The further spectra analysis in the deposited energy space suggested that the total number density of excited species increased with the deposition energy, without significant fluctuations in plasma temperature in the high-energy region.