Reactive fluxes delivered by plasma jets to conductive dielectric surfaces during multiple reflections of ionization waves

Abstract

In this paper, we report results from the computational study of the intersection of the atmospheric pressure plasma jet with a dielectric surface having high conductivity and high dielectric constant. In this case, multiple reflections of the ionization wave (IW) between the jet tube and the surface are observed. We consider the mixture of helium with a small percentage of oxygen (He/O2 = 99.8/0.2), which flows through the jet tube into the ambient humid room air (N2/O2/H2O = 79.5/20/0.5). We evaluate the production and delivery of main ions and reactive oxygen and nitrogen species, which are important for applications in biomedicine. The fluxes and fluences of these species to the dielectric surface are recorded during a single plasma jet pulse of negative polarity. We show that the electron density behind the IW front increases with each passage of the IW between the tube and the surface. With the forward, reflected, and secondary forward IW, there is an essential increase of ions and radicals behind the IW front. The highest increase of radicals and their fluxes is observed after the secondary forward wave bridges the gap and touches the surface.