Measurement and simulation of He and Ar metastable density profiles in radio-frequency micro-plasma jets
Benedikt Niermann, Torben Hemke, Marc Böke, Thomas Mussenbrock, Ralf Peter Brinkmann, Jörg Winter
IX Workshop on Frontiers in Low Temperature Plasma Diagnostics, Zinnowitz, Germany, 09-11 May
Space resolved concentrations of helium He* and argon Ar* metastable atoms in an atmospheric pressure radio frequency micro-plasma jet are measured using tunable diode laser absorption spectroscopy. The spatial profile of metastable atoms in the volume between the electrodes is deduced for various electrode gap distances. Density profiles reveal the sheath structure and reflect the plasma excitation distributions, as well as the dominance of the ?-mode discharge. In order to analyze the experimentally observed profiles of the metastable atoms a 2D numerical simulation was set up. Applying an appropriate He/Ar chemical model the correlation between the profiles of the metastables and the underlying excitation mechanisms is deduced.