Prediction of the spatial location of a laser-induced breakdown in argon

Abstract

A modelling of the laser-induced breakdown spatial location is presented and compared to experiments where the considered variables are the incident laser energy and the initial pressure of argon in the vessel. The proposed modelling is based on the assumption that the conservation of the threshold laser energy per unit surface needs to produce a breakdown. The experiment consists in 100 consecutive laser shots for eight laser energies from 4.48 to 147.81 mJ at λ = 532 nm and four initial pressures, from 0.25 to 1 bar. A dimensionless number, E/Eth, is also proposed to compare all obtained data to each other with E the incident energy and Eth the threshold energy below the one no breakdown appears. The proposed modelling is in good agreement with observed values (<10% in most experiments) and is particularly interesting for laser-induced breakdown spectroscopy in gas where the location of the plasma is of great importance.