Helium plasma jet interaction with different target materials and the plasma characteristics on the irradiation area

The experimental study on the dynamic behavior of helium atmospheric pressure plasma jet exposed on the surface of different conductivity is reported in this article. Electrical, optical, and gas dynamics characteristics are monitored using a high voltage probe, current probe, and imaging technique. The turbulence-free plasma jet length is estimated from the image of the plasma jet and correlated with the length estimated through the Electrohydrodynamic number (Ehd number). It has been shown that plasma species strongly modify the gas dynamics on the contact surface. The irradiation area on agar gel, metal, and Teflon is observed and the different flow regimes (free jet, stagnant region, and accelerating region) are identified. The irradiation area is significantly broadened for the polymer-like substrate and intensity is higher close to the stagnant region. The excited nitrogen and OH intensity is higher than the other observed chemical species on the target surface. The turbulence is higher near the outer radius of the irradiated surface, and it increases with operating voltage. The chemistry of the water changes with the presence of the metal probe inside the water