Influence of Nozzle Shape on the Performance of Low-Power Ar Plasma Jet

The influence of nozzle geometry on the properties of atmospheric-pressure Ar plasma jet was investigated. Three different nozzle types were tested: 1) a tapered nozzle (to get a thin plasma plume); 2) a straight nozzle (used in most cases); and 3) an enlarged nozzle (to increase the active plasma area). The electrical properties and visual appearance of the generated plasma were studied with these three nozzles. The jet's performance for surface modification was evaluated by measuring the area of the samples with enhanced wettability and comparing it with the image analysis of the light emission over the sample surface. It has been concluded that limiting the nozzle diameter can be a solution to reduce the treatment area. However, the decrease in the treated area is limited due to the plasma spreading. The use of widen nozzle leads to increase in the treated area and possibility to control the mixture of the carrier gas with ambient air, making this nozzle configuration potentially interesting for other applications, as, for example, treatment of small 3-D objects.