title: Interferometric investigation of the influence of argon buffer gas on the characteristics of laser-induced aluminum plasmas.
abstract: An interferometric analysis was performed to investigate the influence of argon (Ar) buffer gas on the characteristics of laser-induced aluminum (Al) plasma at atmospheric pressure. The plasma was produced by focusing a Q-switched Nd:YAG laser pulse (λ=1064  nm, pulse duration ∼5  ns, E=6.0  mJ) onto an Al target. The interference patterns were constructed using a Nomarski interferometer incorporated with a frequency-doubled, Q-switched Nd:YAG laser (λ=532  nm, pulse duration ∼10  ns) that generates an interferometric probe beam. The interferometric measurements were carried out as a function of the elapsed time after the onset of breakdown under the conditions of open air and an Ar gas jet flow (5  l/min). With the injection of an Ar buffer gas jet in the ablation process, an increase in electron density and a preferential axial plasma expansion of the plasma plume were observed during the early stages of plasma formation as a consequence of increased inverse-Bremsstrahlung (IB) absorption efficiency.
authors.forename: Seong Y
authors.initials: SY
authors.lastname: Oh
authors.forename: Jagdish P
authors.initials: JP
authors.lastname: Singh
authors.forename: Changhwan
authors.initials: C
authors.lastname: Lim