The influence of air impurities on the evolution of plasma species in a capillary helium plasma jet

The main aim of this paper is to numerically investigate the evolution of the different species in a capillary helium plasma jet, during the plasma bullet propagation. This study is performed in a wide range of air concentrations in the helium jet core (up to 16000 ppm). The simulation results showed that the helium species are only produced and propagated in the helium jet core (axisymmetric line of the tube). On the other hand, the nitrogen and oxygen species (for up to 7000 ppm air in the jet core) were produced and propagated at the side of the jet core. For level of air concentration (in the jet core) higher than 7000 ppm, the production and propagation of the nitrogen and oxygen species converges towards the helium jet core. In order to interpret the results, the mean reaction pathways behind the production of each species are examined. This analysis gives insight into the physics behind the evolution and characteristics of the plasma je