A ps-TALIF diagnostic study of He:O 2 plasma jet driven by tailored voltage waveforms

Le résumé fourni par la source

Abstract Dual-frequency tailored voltage waveforms in the MHz range are applied to an atmospheric-pressure plasma jet source operating in a He:O 2 mixture to enhance atomic oxygen (AO) generation. In previous work, this approach was implemented to increase the AO number density by a factor of 1.5–3 in the discharge region, with limited gas heating. In this further study, the AO number density in the effluent region is quantified using picosecond two-photon absorption laser-induced fluorescence. Effects of oxygen concentration, operational power and harmonic phase shift are systematically investigated and coupled with a 1-D plasma model and a 2D axisymmetric computational fluid dynamics simulation. Both experimental and numerical results reveal a pronounced geometric asymmetry effect, which promotes the AO population in the jet center. By superimposing a harmonic component onto the driving waveform with a relative phase of θ = 270°, an electric asymmetry effect (EAE) is induced via modification of the sheath dynamics. This leads to an overall enhancement of AO density in the effluent, particularly in the far field. In contrast, shifting the harmonic phase to θ = 90° reverses the EAE, thereby limiting AO generation. Compared with the phase-modulation effects on plasma sources, the changes in the effluent region are more limited due to the interaction between the plasma jet and the entrained ambient air. This study demonstrates effective waveform-based control of AO production and transport in atmospheric-pressure plasma jets, providing new insights into the processing of heat-sensitive materials with plasma jets.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.