O₂ influence on the spatio-temporal density of Ar(1s5) in micro-plasma jets with varying shieldings

Argon micro-plasma jets (AMPJs) can be created by streamers propagating along the jet [1], which excite argon species that interact with air [2] or targets [3]. Jets lead to the admixture of ambient species into the main flow, resulting in discharges produced in evolving gas compositions.

We studied the influence of air on a pure AMPJs (1 slm) produced by a square-pulsed sDBD, with two discharges per applied voltage pulse. Using laser absorption spectroscopy, we measured spatiotemporal Ar(1s5) absorbance profiles, to compare its quenching in different N₂-O₂ shieldings in a co-flow reactor (0.1 to 3 slm and ~0 to 100% of O₂). We processed this data into spatiotemporal density and effective-lifetime profiles of Ar(1s5), for both discharges.

Absence of O₂ leads to the lowest peak Ar(1s5) density for both discharges and lowers the reproducibility of the first. Increasing O₂ fraction increases the propagation velocity of the first discharge and decreases that of the second, with temporal profiles further altered with the radius.

Isolating the effect of O₂ on AMPJs could be helpful for future applications, and the obtained data can help validate computational models.