| Abstract: | Laser‐induced thermal acoustics is used to measure non‐intrusively the concentration of a resonantly excited seed species (iodine vapor) diluted within a non‐resonantly excited species (nitrogen) by comparing the contributions from thermalization and electrostriction to the density perturbations of a density grating, which is inscribed in the fluid by two pulsed intersecting laser beams. The ratio of the characteristic density perturbation caused by thermalization to the perturbations from electrostriction is proportional to the concentration of the resonant species. The ratio is found by a least‐squares fit of a closed‐form analytical model to the data. When the importances of thermalization and electrostriction are comparable, the uncertainty for the concentration is 5%, but higher when one mechanism's contributions outweigh the other's greatly. |
