Influence of the nozzle head geometry on the energy flux of an atmospheric pressure plasma jet

The influence of different nozzle head geometries and, therefore, the variation of the excitation and relaxation volume on the energy flux from an atmospheric pressure plasma jet to a surface have been investigated. Measurements have been performed by passive calorimetric probes under variation of the gas flow through the nozzle. The results show that the geometry of the nozzle head has a significant impact on the resulting energy flux. The relaxation volume affects the dependence of the energy flux on the gas flow. While there is no significant influence of the working gas flow on the energy flux without a relaxation volume, utilizing a relaxation volume leads to a decrease of the energy flux with increasing working gas flow. Within the analyzed parameter range, the energy flux reveals for both nozzle heads a linear dependency on the applied primary voltage.