Determination of the Energy Flux of a Commercial Atmospheric‐Pressure Plasma Jet for Different Process Gases and Distances Between Nozzle Outlet and Substrate Surface

The energy flux of an atmospheric-pressure plasma jet for surface treatment has been investigated by a calorimetric probe. Generally, the investigations exhibit that the main contributions of the total energy influx from the plasma to the substrate surface originate from the neutrals regarding high gas temperature coupled with a high gas flow. The use of nitrogen as process gas shows a higher energy flux compared to oxygen and air presumably caused by increased gas temperature as well as by higher molecule formation and recombination energy of N-2. Moreover, the lateral expansion of the plasma beam could be roughly determined by a spatially resolved analysis of the energy influx. A top part mounted on the nozzle, commonly used for the injection of additional precursor gases, showed a significant effect on the flow behavior and collision entailed relaxation of the excited plasma species leading to a restraining of the plasma jet. ((c) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)