A poly-diagnostic study of the shield gas-assisted atmospheric pressure plasma jet propagation upon a dielectric surface

The significance of shield gases on atmospheric pressure plasma jet (APPJ) propagation over a horizontal dielectric surface using various diagnostic methods has been investigated. The obtained results imply that adding nitrogen as a shield gas only has an impact on the N2 reactive species generation, mainly close to the plasma effluent while argon shield gas can boost the optical emission intensity of all excited species, especially at distances further away from the plasma jet, which is in agreement with the observed length of the plasma propagation all over the surface. On the basis of the obtained results, the employment of a shield gas can improve the plasma jet efficiency to achieve the desired treatment effect on a flat surface.